第一篇:高三專(zhuān)題復(fù)習(xí)教案 8 物理問(wèn)題的解題技巧
[高三物理熱點(diǎn)專(zhuān)題] 考點(diǎn)8 物理問(wèn)題的解題技巧
命題趨勢(shì)
高考越來(lái)越注重考能力,從一定意義上說(shuō)方法是能力的基礎(chǔ).但高考不會(huì)純粹考方法.方法的考查一般會(huì)采取隱性的形式,滲透在具體的物理問(wèn)題中.
同時(shí),能力不僅僅體現(xiàn)在能否把一道題解出來(lái),更體現(xiàn)在是否解得巧妙、是否快捷上.2000年理綜試卷中,有一道三個(gè)電阻星形連接的實(shí)驗(yàn)題;測(cè)三次電阻,列三個(gè)方程的一般思路,很多同學(xué)都能想到,難度并不大,但方程解起來(lái)極其繁瑣.而命題者的意圖是考查考生能否想出另一種簡(jiǎn)捷的解法,考的是方法.這里,方法的考查涉及的不光是這一道題的得分,還涉及到是否能給別的題留出充裕的時(shí)間,提高整卷的分值. 知識(shí)概要
中學(xué)物理教學(xué)大綱明確指出:“要重視概念和規(guī)律的應(yīng)用,使學(xué)生學(xué)會(huì)運(yùn)用物理知識(shí)解釋現(xiàn)象,分析和解決實(shí)際問(wèn)題”,這就是說(shuō),不僅要運(yùn)用物理知識(shí)解決實(shí)際問(wèn)題,而且要有意識(shí)的領(lǐng)悟物理解題的思維方法.
中學(xué)物理所涉及的科學(xué)思維方法,以及由此而產(chǎn)生的解題技巧和方法很多,本專(zhuān)題僅對(duì)其中幾種作一介紹:
一、整體法和隔離法
在解答物理問(wèn)題時(shí),往往會(huì)遇到有相互作用的兩個(gè)物體或兩個(gè)以上的物體所組成的比較復(fù)雜的系統(tǒng).分析和解答這類(lèi)問(wèn)題,確定研究對(duì)象是關(guān)鍵.對(duì)系統(tǒng)內(nèi)的物體逐個(gè)隔離進(jìn)行分析的方法稱(chēng)為隔離法;把整個(gè)系統(tǒng)作為一個(gè)對(duì)象進(jìn)行分析的方法稱(chēng)為整體法. 隔離法的優(yōu)點(diǎn)在于能把系統(tǒng)內(nèi)各個(gè)物體所處的狀態(tài)、物體狀態(tài)的變化的原因以及物體間相互作用關(guān)系分析清楚,能把物體在系統(tǒng)內(nèi)與其他物體相互作用的內(nèi)力轉(zhuǎn)化為物體所受的外力,以便應(yīng)用牛頓第二定律進(jìn)行求解.缺點(diǎn)是涉及的因素多比較繁雜. 整體法的優(yōu)點(diǎn)是只須分析整個(gè)系統(tǒng)與外界的關(guān)系,避開(kāi)了系統(tǒng)內(nèi)部繁雜的相互作用,更簡(jiǎn)潔、更本質(zhì)的展現(xiàn)出物理量間的關(guān)系.缺點(diǎn)是無(wú)法討論系統(tǒng)內(nèi)部的情況.
一般地說(shuō),對(duì)于不要求討論系統(tǒng)內(nèi)部情況的,首選整體法,解題過(guò)程簡(jiǎn)明、快捷;要討論系統(tǒng)內(nèi)部情況的,必須運(yùn)用隔離法.實(shí)際應(yīng)用中,隔離法和整體法往往同時(shí)交替使用.
二、等效法
等效法就是在保證某一方面效果相同的前提下,用理想的、熟悉的、簡(jiǎn)單的物理對(duì)象、物理過(guò)程、物理現(xiàn)象替代實(shí)際的、陌生的、復(fù)雜的物理對(duì)象、物理過(guò)程、物理現(xiàn)象的思想方法.合力與分力、運(yùn)動(dòng)的合成與分解、電阻的串聯(lián)與并聯(lián)、交流電的有效值等都是等效法在物理學(xué)中的實(shí)際應(yīng)用.
等效法在物理解題中也有廣泛的應(yīng)用,主要有:物理模型的等效替代;物理過(guò)程的等效替代;作用效果的等效替代. 在應(yīng)用等效法解題時(shí),應(yīng)知道兩個(gè)事物的等效不是全方位的,只是局部的,特定的、某一方面的等效.因此在具體的問(wèn)題中必須明確哪一方面等效,這樣才能把握住等效的條件和范圍.
三、對(duì)稱(chēng)法
自然界和自然科學(xué)中,普遍存在著優(yōu)美和諧的對(duì)稱(chēng)現(xiàn)象.對(duì)稱(chēng)性就是事物在變化時(shí)存在的某種不變性.物理中對(duì)稱(chēng)現(xiàn)象比比皆是,對(duì)稱(chēng)的結(jié)構(gòu)、對(duì)稱(chēng)的作用、對(duì)稱(chēng)的電路、對(duì)稱(chēng)的物和像等等.一般情況下對(duì)稱(chēng)表現(xiàn)為研究對(duì)象在結(jié)構(gòu)上的對(duì)稱(chēng)性、物理過(guò)程在時(shí)間上和空間上的對(duì)稱(chēng)性、物理量在分布上的對(duì)稱(chēng)性及作用效果的對(duì)稱(chēng)性等.
利用對(duì)稱(chēng)性解題時(shí)有時(shí)能一眼看出答案,大大簡(jiǎn)化解題步驟.從科學(xué)思維方法的角度來(lái)講,對(duì)稱(chēng)性最突出的功能是啟迪和培養(yǎng)學(xué)生的直覺(jué)思維能力.用對(duì)稱(chēng)性解題的關(guān)鍵是敏銳地看出并抓住事物在某一方面的對(duì)稱(chēng)性,這些對(duì)稱(chēng)性往往就是通往答案的捷徑. 點(diǎn)撥解疑
【例題1】
如圖1所示,甲、乙兩個(gè)帶電小球的質(zhì)量均為m,所帶電量分別為q和-q,兩球間用絕緣細(xì)線(xiàn)連接,甲球又用絕緣細(xì)線(xiàn)懸掛在天花板上,在兩球所在的空間有方向向左的勻強(qiáng)電場(chǎng),電場(chǎng)強(qiáng)度為E,平衡時(shí)細(xì)線(xiàn)都被拉緊.
(1)平衡時(shí)可能位置是圖1中的()
(2)
1、2兩根絕緣細(xì)線(xiàn)的拉力大小分別為()A.F1?2mg,F(xiàn)2?C.F1?2mg,F(xiàn)2?
(mg)2?(Eq)B.F1?2mg,F(xiàn)2?(mg)2?(Eq)2(mg)2?(Eq)2
D.F1?2mg,F(xiàn)2?(mg)2?(Eq)2
【點(diǎn)撥解疑】(1)若完全用隔離法分析,那么很難通過(guò)對(duì)甲球的分析來(lái)確定上邊細(xì)繩的位置,好像A、B、C都是可能的,只有D不可能.用整體法分析,把兩個(gè)小球看作一個(gè)整體,此整體受到的外力為豎直向下的重力2mg,水平向左的電場(chǎng)力qE(甲受到的)、水平向右的電場(chǎng)力qE(乙受到的)和上邊細(xì)繩的拉力;兩電場(chǎng)力相互抵消,則繩1的拉力一定與重力(2mg)等大反向,即繩1一定豎直,顯然只有A、D可能對(duì).
再用隔離法,分析乙球受力的情況.乙球受到向下的重力mg,水平向右的電場(chǎng)力qE,繩2的拉力F2,甲對(duì)乙的吸引力F引.要使得乙球平衡,繩2必須傾斜,如圖2所示.故應(yīng)選A.(2)由上面用整體法的分析,繩1對(duì)甲的拉力F1=2mg.由乙球的受力圖可知
22F2?F引?(mg)?(qE)
因此有F2?(mg)2?(qE)2應(yīng)選D 點(diǎn)評(píng):若研究對(duì)象由多個(gè)物體組成,首先考慮運(yùn)用整體法,這樣受力情況比較簡(jiǎn)單,在本題中,馬上可以判斷繩子1是豎直的;但整體法并不能求出系統(tǒng)內(nèi)物體間的相互作用力,故此時(shí)需要使用隔離法,所以整體法和隔離法常常交替使用.
【例題2】(1994年高考全國(guó)卷)如圖3所示,質(zhì)量M=10kg的木楔ABC靜止于粗糙的水平面上,動(dòng)摩擦因數(shù)μ=0.02.在楔的傾角為θ=30°的斜面上,有一質(zhì)量m=1.0kg的木塊從靜止開(kāi)始沿斜面下滑,當(dāng)滑行路程s=1.4m時(shí),其速度v=1.4m/s,在這過(guò)程中楔沒(méi)有動(dòng),求地面對(duì)楔的摩擦力的大小和方向(重力加速度取10m/s2).
【點(diǎn)撥解疑】 若采用隔離法,分析楔M時(shí),受的力特別多,求解繁瑣.該題中,雖然m與M的加速度不同,但仍可用整體法,只是牛頓第二定律應(yīng)寫(xiě)成
?F外?m1a1?m2a2
2由v2?vo?2as
v21.42??0.7m/s 得木塊m沿斜面向下運(yùn)動(dòng)的加速度為 a?2s2?1.4將物塊m和木楔M看作一個(gè)整體,他們?cè)谪Q直方向受到重力和地面的支持力;在水平方向如果受力只能是摩擦力,暫設(shè)其存在,大小位Ff,楔的加速度為零,只有物塊加速度a,如圖4所示,沿水平方向和豎直方向分解物塊加速度a.對(duì)整體在水平方向上運(yùn)用牛頓第二定律,得 Ff?max?macos?
解得
Ff = 0.4N 因?yàn)镕f應(yīng)與ax同向
所以木楔受到的摩擦力水平向左.
點(diǎn)評(píng):若一個(gè)系統(tǒng)內(nèi)各個(gè)物體的加速度不相同,又不需要求系統(tǒng)內(nèi)物體間的相互作用力時(shí),利用牛頓第二定律應(yīng)用整體法解題方便很多.本題也可以用隔離法求解,請(qǐng)同學(xué)們?cè)囈辉嚕?/p>
【例題3】如圖5所示,輕彈簧的一端固定在地面上,另一端與木塊B相連,木塊A放在木塊B上,兩木塊質(zhì)量均為m,在木塊A上施有豎直向下的力F,整個(gè)裝置處于靜止?fàn)顟B(tài).
(1)突然將力F撤去,若運(yùn)動(dòng)中A、B不分離,則A、B共同運(yùn)動(dòng)到最高點(diǎn)時(shí),B對(duì)A的彈力有多大?
(2)要使A、B不分離,力F應(yīng)滿(mǎn)足什么條件?
【點(diǎn)撥解疑】 力F撤去后,系統(tǒng)作簡(jiǎn)諧運(yùn)動(dòng),該運(yùn)動(dòng)具有明顯的對(duì)稱(chēng)性,該題利用最高點(diǎn)與最低點(diǎn)的對(duì)稱(chēng)性來(lái)求解,會(huì)簡(jiǎn)單的多.
(1)最高點(diǎn)與最低點(diǎn)有相同大小的回復(fù)力,只有方向相反,這里回復(fù)力是合外力.在最低點(diǎn),即原來(lái)平衡的系統(tǒng)在撤去力F的瞬間,受到的合外力應(yīng)為F/2,方向豎直向上;當(dāng)?shù)竭_(dá)最高點(diǎn)時(shí),A受到的合外力也為F/2,但方向向下,考慮到重力的存在,所以B對(duì)A的彈力為mg?F. 2(2)力F越大越容易分離,討論臨界情況,也利用最高點(diǎn)與最低點(diǎn)回復(fù)力的對(duì)稱(chēng)性.最高點(diǎn)時(shí),A、B間雖接觸但無(wú)彈力,A只受重力,故此時(shí)恢復(fù)力向下,大小位mg.那么,在最低點(diǎn)時(shí),即剛撤去力F時(shí),A受的回復(fù)力也應(yīng)等于mg,但根據(jù)前一小題的分析,此時(shí)回復(fù)力為F/2,這就是說(shuō)F/2=mg.則F=2mg.因此,使A、B不分離的條件是F≤2mg. 【例題4】
圖6為電壓表和電流表測(cè)定電源的電動(dòng)勢(shì)和內(nèi)電阻的電路圖,采用的是電流表外接法.若已知電壓表和電流表的內(nèi)電阻分別為RV和RA,試計(jì)算用這個(gè)電路測(cè)得的電動(dòng)勢(shì)及內(nèi)電阻的相對(duì)誤差.
【點(diǎn)撥解疑】按實(shí)驗(yàn)原理的要求,電流表和電壓表的讀數(shù)應(yīng)分別是總電流和路端電壓.從電路結(jié)構(gòu)看,電流表讀數(shù)確是總電流,但由于電流表有電阻,所以電壓表的讀數(shù)不是路端電壓,這樣就造成系統(tǒng)誤差.
運(yùn)用等效法把電源和電流表作為一個(gè)整體看成一個(gè)新的等效電源,如圖7中虛線(xiàn)框所示,此時(shí)電壓表確實(shí)接在這個(gè)新電源的兩端,讀數(shù)確是路端電壓,而此時(shí)電流表的讀數(shù)仍表示總電流.因此根據(jù)電壓表和電流表的讀數(shù)測(cè)得的E和r是這個(gè)新電源的電動(dòng)勢(shì)和內(nèi)電阻的真實(shí)值.
新電源實(shí)際上是由電池和電阻RA串聯(lián)而成,設(shè)電池的電動(dòng)勢(shì)和內(nèi)電阻分別是E0和r0,應(yīng)有如下對(duì)應(yīng)關(guān)系
E= E0
r= r0+RA
相對(duì)誤差分別為
?E?0
?r? 針對(duì)訓(xùn)練
1.如圖8所示,一塊均勻的半圓形薄電阻合金片,現(xiàn)將它按圖甲方式接在電極A、B之間,求其電阻值.(電極電阻忽略不計(jì))
r?r0RA ?r0r?RA
2.三個(gè)質(zhì)量、形狀相同的斜面體放在粗糙的水平地面上,另有三個(gè)質(zhì)量相同的小物體從斜面頂端沿斜面滑下,由于小物體與斜面間的摩擦力不同,第一個(gè)物體勻加速下滑,第二個(gè)物體勻速下滑,第三個(gè)物體以初速度v0勻減速下滑,如圖9所示,三個(gè)斜面均保持不動(dòng),則下滑過(guò)程中斜面對(duì)地面壓力 A.F1?F2?F
3B.F1?F2?F3 C.F1?F2?F3
D.F1?F2?F3
3.如圖10所示電路由8個(gè)不同的電阻組成,已知R1=12Ω,其余電阻阻值未知,測(cè)得A、B間的總電阻為4Ω,今將R1換成6Ω的電阻,則A、B間的總電阻變?yōu)?/p>
4.用細(xì)塑料棒彎成半徑為R的圓弧,如圖11所示,A、B間的空隙為l,R>>l.將電量為Q的正電荷均勻分布于環(huán)上,求圓心O處的電場(chǎng)強(qiáng)度.
5.如圖12所示,在平行于水平地面的有理想邊界的勻強(qiáng)磁場(chǎng)上方,有三個(gè)大小相同的正方形線(xiàn)框,線(xiàn)框平面與磁場(chǎng)方向垂直.三個(gè)線(xiàn)框是用相同的金屬材料制成的,A線(xiàn)框有一個(gè)缺口,B、C線(xiàn)框都閉合,但B線(xiàn)框?qū)Ь€(xiàn)的橫截面積比C線(xiàn)框大.現(xiàn)將三個(gè)線(xiàn)框從同一高度由靜止開(kāi)始同時(shí)釋放,下列關(guān)于它們落地時(shí)間的說(shuō)法正確的是
A.三個(gè)線(xiàn)框同時(shí)落地
B.三個(gè)線(xiàn)框中,A線(xiàn)框最早落地
C.B線(xiàn)框在C線(xiàn)框之后落地
D.B線(xiàn)框和C線(xiàn)框在A(yíng)線(xiàn)框之后同時(shí)落地
6.如圖13所示,在h高度處,距離豎直壁為d的O點(diǎn),有一小球以初速度v0沿水平方向拋出,它與墻壁發(fā)生彈性碰撞后落到水平地面上,求小球落地點(diǎn)到墻壁的距離. 7.兩塊質(zhì)量分別為m1和m2的木塊,用一根勁度系數(shù)為k的輕彈簧連在一起,現(xiàn)在m1上施加壓力F,如圖14所示.為了使撤去F后m1跳起時(shí)能帶起m2,則所加壓力F應(yīng)多大?
8.如圖15所示,將質(zhì)量分別為m、2m、3m的三個(gè)小球A、B、C用絕緣細(xì)線(xiàn)相連,其中B球帶+Q電量,A、C兩球不帶電,并將A球固定住,三球均處于靜止?fàn)顟B(tài).A、B間細(xì)線(xiàn)的張力等于多少?在將A球從靜止釋放的一小段時(shí)間內(nèi),A、B間細(xì)線(xiàn)的張力等于多少?
9.如圖16所示,設(shè)A重10N,B重20N,A、B間的動(dòng)摩擦因數(shù)為0.1,B與地面的動(dòng)摩擦因數(shù)為0.2.問(wèn):(1)至少對(duì)B向左施多大的力,才能使A、B發(fā)生相對(duì)滑動(dòng)?(2)若A、B間有μ1=0.4,B與地間有μ=0.l,則F多大才能產(chǎn)生相對(duì)滑動(dòng)? 10.如圖17所示,在兩塊相同的豎直木板間,有質(zhì)量均為m的四塊相同的磚,用兩個(gè)大小均為F的水平力壓木板,使磚靜止不動(dòng),則左邊木板對(duì)第一塊磚,第二塊磚對(duì)第三塊磚的摩擦力分別為:
A.4mg、2mg
B.2mg、0
C.2mg、mg
D.4mg、mg
圖 17
圖 16 11.有一個(gè)直角支架 AOB,AO水平放置,表面粗糙,OB豎直向下,表面光滑,AO上套有小環(huán)P,OB上套有小環(huán) Q,兩環(huán)質(zhì)量均為m,兩環(huán)間由一根質(zhì)量可忽略、不可伸展的細(xì)繩相連,并在某一位置平衡(如圖18),現(xiàn)將P環(huán)向左移一小段距離,兩環(huán)再次達(dá)到平衡,那么將移動(dòng)后的平衡狀態(tài)和原來(lái)的平衡狀態(tài)比較,AO桿對(duì)P環(huán)的支持力N和細(xì)繩上的拉力T的變化情況是:
A.N不變,T變大
B.N不變,T變小 C.N變大,T變大
D.N變大,T變小 參考答案
1.4R(對(duì)稱(chēng)法)2.C(整體法)3.3Ω(等效法)4.
圖 18 kQl
方向由圓心指向弧AB的中點(diǎn)(等效法和對(duì)稱(chēng)法)
(2?R?l)R27 5.BD(等效法)6.v02h?d(對(duì)稱(chēng)法)g7.F?(m1?m2)g(對(duì)稱(chēng)法)
8.qE?5mg
qE/3(整體法和隔離法)
9.解析:(1)設(shè)A、B恰好滑動(dòng),則B對(duì)地也要恰好滑動(dòng),選A、B為研究對(duì)象,由平衡條件得:
F=f地+2T
選A為研究對(duì)象,由平衡條件有
T=fA
fA=0.1×10=1N
f地=0.2×30=6N ∴
F=8N.
(2)同理解得,F(xiàn)=11N 10.解析:由對(duì)稱(chēng)性,左、右木板對(duì)磚摩擦力相同,設(shè)為f1,第 3塊磚對(duì)第2塊磚摩擦力為f2,則對(duì)四塊磚整體有:2f1=4mg
∴
f1=2mg
對(duì)1、2塊磚平衡有:f1+f2=2mg ∴
f2=0 故B正確.
11.解析:設(shè)PQ與OA的夾角為α,對(duì) P有: mg+Tsinα=N 對(duì)Q有:Tsinα=mg 所以
N=2mg,T=mg/sinα 答案為B.
第二篇:高三英語(yǔ)復(fù)習(xí)課教案8
高三英語(yǔ)復(fù)習(xí)課教案8
名詞從句(Noun Clauses)I.Teaching Aims:
To ask the students to master the usage of noun clauses and use it freely when communicating with each other.II.Difficulties and Emphasis: ** How to distinguish the noun clauses.**How to tell the appositive clause from the attributive clause.III.Teaching Tools: Multi—media IV.Teaching Processes: Step1.Review the Attributive clause.(5 minutes)
Step2.Presentation(computer)
(5 minutes)Showing the students some sentences, ask them to analyse the sentences, making sure they can tell every part of speech, especially subject、object、predictive and appositive.Step3.Explanation
(Looking at the screen)(15 minutes)The usage of noun clauses: 名詞從句包括主語(yǔ)、賓語(yǔ)、表語(yǔ)和同位語(yǔ)等從句。它們可以由下列連詞引導(dǎo):從屬連詞 that, whether, if;連接代詞 who(ever), whom, whose, what(ever), which(ever);連接副詞 when, where, why, how, how much / many /long /often 等。
●主語(yǔ)從句在句中作主語(yǔ)
That mathematics finds its use in every science is evident.Whoever is tired may rest.Why the earth moves round the sun is quite clear now.主語(yǔ)從句常放在句尾而用 it 作形式主語(yǔ)使句子更加平衡,這時(shí)口語(yǔ)中常省略 that, 如上面第一句改成“It is evident(that)mathematics finds its use in every science.”更好。在下列情況下必須把主語(yǔ)從句放在句尾而用 it 作形式主語(yǔ):
1. 主句謂語(yǔ)是被動(dòng)語(yǔ)態(tài)時(shí),如:
It is said that he is a good doctor.2. 主句是疑問(wèn)句或感嘆句時(shí),如:
Is it true that the film star will come?
How wonderful it is that we'll visit the Great Wall tomorrow.3. 主句謂語(yǔ)動(dòng)詞是 appear, turn out, happen, occur, come, strike, follow, matter 等時(shí),如:
It happened that she had a cold and didn't go with us that day.It turned out that I was wrong.4. 表示說(shuō)話(huà)人的推測(cè)或評(píng)價(jià),如在 it seems, it may be, it is(un)likely, it is(im)possible, it is a pity, it is a wonder 等結(jié)構(gòu)中,如:
It seems that this test is reliable.It is a pity(that)she can't go with us.5. 強(qiáng)調(diào)主句的表語(yǔ)時(shí),如:
It is a mystery to me how it all happened.It is necessary that he should do so.●賓語(yǔ)從句在句中作賓語(yǔ)
I thought(that)you had read the book.We should learn to tell whether an element is poisonous or not.Do you know who invented this? 1. 賓語(yǔ)從句后有賓語(yǔ)補(bǔ)足語(yǔ)時(shí)常移至句末,而用 it 做形式賓語(yǔ)放在前面,如:
The experiment makes it clear that air has pressure.2 賓語(yǔ)從句可作某些介詞和某些作表語(yǔ)用的形容詞的賓語(yǔ),如:
The resistance of a wire also depends upon what material it is made of.We are sure(that)it will be a success.3. 賓語(yǔ)從句可以是直接引語(yǔ)也可以是間接引語(yǔ),如:
He asked me, “Are you from Chengdu?”(直接引語(yǔ))
He asked me whether I was from Chengdu.(間接引語(yǔ))
●表語(yǔ)從句在句中作表語(yǔ)
The reason is(that)we haven't raised enough money.That is what we want to know.●同位語(yǔ)從句在句中作補(bǔ)充說(shuō)明名詞及其短語(yǔ)的從句
I am in doubt whether I should buy or not.He expressed his hope that he would visit China again.Step4.Practice.Doing some exercises(filling the blanks)
(15 minutes)Step5.Disscusion of the defrences of the attributive clause and apposive clause.(3 minutes)Step6.Consolidition
(1 minutes)Step7.Homework.(Making some sentences with noun clauses)
(1 minutes)
第三篇:高三英語(yǔ)復(fù)習(xí)閱讀理解解題技巧教案
高三英語(yǔ)復(fù)習(xí):閱讀理解解題技巧
【本課目標(biāo)】:復(fù)習(xí)閱讀理解解題技巧,讓學(xué)生了解高考考試說(shuō)明里閱讀理解考點(diǎn),對(duì)于不同題型會(huì)運(yùn)用不同的解題技巧答題,讓學(xué)生在考試和練習(xí)中能夠主動(dòng)運(yùn)用該技巧答題,從而提高閱讀速度,提高成績(jī)
【本課重點(diǎn)】:閱讀理解在高考題型中的重點(diǎn)考察形式;如何運(yùn)用各種技巧來(lái)解答閱讀理解的各種題型
【Teaching procedures】:
Step 1.Review some language points of last period in Unit13.Step 2.了解福建高考考試說(shuō)明里閱讀理解的要求:(1)理解文章主旨要義(2)理解文中具體信息
(3)根據(jù)上下文推斷生詞的詞義(4)作出簡(jiǎn)單判斷和推測(cè)(5)理解文章的基本結(jié)構(gòu)
(6)理解作者的意圖、觀(guān)點(diǎn)和態(tài)度 Step3.對(duì)于考試說(shuō)明里這六種題型(1)理解文章主旨要義(2)理解文中具體信息
(3)根據(jù)上下文推斷生詞的詞義(4)作出簡(jiǎn)單判斷和推測(cè)(5)理解文章的基本結(jié)構(gòu)
(6)理解作者的意圖、觀(guān)點(diǎn)和態(tài)度 的定義、提問(wèn)的類(lèi)型、解題的技巧、方法給予詳細(xì)介紹并結(jié)合例子給予解釋說(shuō)明。Step 3.閱讀理解解題技巧總結(jié)
1、切忌的閱讀方法。
2、在閱讀速度方面,要以較快的速度從大量材料中捕捉有關(guān)信息,學(xué)生必須養(yǎng)成良好的將遇良才習(xí)慣,不是逐詞閱讀,而是按意群(meaningful group)掃視、連貫閱讀;是拘泥于個(gè)別詞句的理解,而力求融會(huì)貫通、掌握通篇的中心思想;不是通過(guò)翻譯來(lái)理解,而是使英語(yǔ)的文字在大腦里直接產(chǎn)生意義。只有這樣,閱讀速度才能加快,理解的準(zhǔn)確率才會(huì)提高
一、事實(shí)細(xì)節(jié)題解題技巧
二、單詞,短語(yǔ)句子意義理解題解題技巧
三、推理判斷題
四、主旨大意題
五、文章語(yǔ)氣,作者態(tài)度題
實(shí)戰(zhàn)出真知識(shí),技巧是大量實(shí)踐中總結(jié)出來(lái)的,要想真正掌握技巧,還得回到實(shí)戰(zhàn)中去.Practice makes perfect!
第四篇:高三教案8
014年暑假高三英語(yǔ)學(xué)習(xí)輔導(dǎo)學(xué)習(xí)單
(八)I.詞匯積累M7U4 Should the opportunity a_______ , I’d love to go to China.If I criticize him, he will get a________ , and start shouting.She’s never p________ in handing in her assignment;she’s always late.In 1968, the Oscar ceremony was p_______ for two days, following the assassination(暗殺)of Martin Luther King.Due to circumstances b________ our control the performance has had to be cancelled.Police have arrested twenty people, accused of _________(違背)a ban on demonstrations.It’s u_________ that the same event happened years later at the same place.He comes back to see his family at regular _______(間隔).She claimed for the ________(所有權(quán))of the house after her parents died.The Three Gorges Dam is the biggest engineering project ever u________ in our country.II句型探究
有關(guān)it的幾個(gè)特殊句型 :
(1)owe it to sb.that…把…歸功于…
虧你幫忙,我才及時(shí)完成了工作。
(2)take it for granted that …想當(dāng)然
我認(rèn)為他們會(huì)支持這個(gè)提議是理所當(dāng)然的。
(3)keep it in mind that…
一定要記住的是成功的秘密是努力的工作。
(4)It can be seen from the statistics that...從這個(gè)統(tǒng)計(jì)可看出……
從這個(gè)統(tǒng)計(jì)可以看出,練習(xí)對(duì)我們是有好處的。
(5).It用在不能直接跟賓語(yǔ)從句的動(dòng)詞后面,尤其是表示好惡的動(dòng)詞后,enjoy, like, love, dislike, resent, hate, don't mind, be fond of, feel like, see to, appreciate, stand 句緊跟it之后
我妒嫉你游泳那么好,而我不能。
如果你晚上給我回電話(huà),我會(huì)非常感激.我無(wú)法忍受別人說(shuō)話(huà)的時(shí)候滿(mǎn)嘴食物.(6).It用在不能直接跟賓語(yǔ)從句的介詞后面,賓語(yǔ)從句緊跟it之后(except that例外)
我贊成你采納他們的意見(jiàn)。
(7)It must be pointed out that
必須指出的是
一定要指出的是國(guó)家基本政策之一是在提高人口質(zhì)量的同時(shí)控制人口增長(zhǎng)。
(8)It has been proved that…
有人已經(jīng)證實(shí)……
已經(jīng)證明,他的理論是對(duì)的。
III題型策略(任務(wù)型閱讀)單句訓(xùn)練
詞性的一致
1.Without vitamin B, we could be
weak and would not grow fast.2.The problems caused by lack of vitamin B are _________ and slow growth.Practice 1.Is it possible for the police to find the lost boy? Is there any ___________ that the police will find the lost boy? 2.As far as I can remember, my friends and I didn’t find out we were depressed until we were in high school.we never experienced ____________when we were in childhood.2.詞的活用
a)同義詞/反義詞
賓語(yǔ)從1.Most workers were for ____________ the decision.2.She didn’t pass the exam.She _____ the exam.b)前綴/后綴
3.Many people lost their houses.Many people became _________.c)句型
4.She didn’t come back until yesterday.She __________ there until yesterday.How to use another word to express the same meaning as the one in the passage 1.Use a synonym
Children act more like adults than they used to.Children today _____________as if they were adults.3.詞的固定搭配
When they entered the room, they saw something strange.When they entered the room, they _________something strange.4.抓關(guān)鍵詞
The surprisingly overcrowded tube crossing the centre of the city is another problem.Another problem is ___________________.隨堂檢測(cè):.Kate was born in China.Kate’s ____________ is China.He didn’t pass the final examination.He _______ the final examination.3.Tom couldn't agree with his boss’s decision more.Tom __________his boss’s decision.4.The lady was not happy.The lady was __________.5.As we all know, if someone wants to pass this exam, he ought to prepare for it well.Good ____________ is key to passing this exam.考綱示例: 1.E-mail has also changed the speed with which we exchanged information.In minutes , you can contact another person.It has also enabled us to exchange information at ________ speed than traditional communicative methods.2.In minutes, you can contact another person who shares your love of kites or stamps.Within a short time, it lets us contact another person who has interest in_________.段落訓(xùn)練
1.利用關(guān)鍵詞意譯(paraphrase)
The first men to cross North America went this slow way.It took them a year and a half to go from St.Louis to the Pacific Ocean.There were no road to follow, and rivers were often rough.The first explorers to cross North America made a ___________and ___________ trip to the Pacific Ocean.: to express something in another way E.g.Footprints are one of the few pieces of hard evidence supporting the idea that
there is Yeti.Footprints are one of the few pieces of hard evidence that support the _________ of Yeti.2.利用關(guān)鍵詞總結(jié)主旨大意(summarize)
Everyone says the parent-teacher conference should be pleasant, civilized, a kind of dialogue where parents and teachers build partnership.But what most teachers feel, and certainly what all parents feel, is anxiety and panic.The __________ between assumption(假設(shè))and reality 篇章訓(xùn)練(M2,U1)In 1998, an American mountain climber said that he saw a Yeti…
Ten Chinese engineers also reported that they saw a Yeti in the Shennongjia National Forest Park in western Hubei Province…
In 1970, 1,089 footprints were discovered in the snow near Washington in the Untied States… an American mountain climber
_________ of the existence of Yeti
Ten Chinese engineers
1,089 footprints 語(yǔ)法提升: 強(qiáng)調(diào)結(jié)構(gòu)
It is I who am wrong.It is in a small factory that my brother is going to work.It is /was +強(qiáng)調(diào)部分+that(who/whom)+其他成分 They will have a meeting in the hall tomorrow.強(qiáng)調(diào)主語(yǔ) 強(qiáng)調(diào)賓語(yǔ) 強(qiáng)調(diào)地點(diǎn)狀語(yǔ) 強(qiáng)調(diào)時(shí)間狀語(yǔ)
2.強(qiáng)調(diào)句型的注意點(diǎn)
It is Mary who often ____(help/helps)me with my English.It is I that ____(be)against you.It is the boy students of Class Two who ____ playing football on the playground.這次得冠軍的是她。
It was ____ that won the championship this time.你明天要去采訪(fǎng)的是他。③
be前面可加情態(tài)動(dòng)詞 ④問(wèn)句形式:
一般問(wèn)句:Is/Was it + 被強(qiáng)調(diào)部分
+ that +----
特殊問(wèn)句:疑問(wèn)詞+is/was +it +that +-----他想申請(qǐng)的是這家公司嗎?
________________ that he wants to apply for? 你們是在哪里買(mǎi)到這本小說(shuō)的?
⑤
當(dāng)強(qiáng)調(diào)not…until結(jié)構(gòu)時(shí),必須將
not until連用,后面接肯定式。The teacher didn’t stop his lesson until the bell rang.(改成強(qiáng)調(diào)句)
3.強(qiáng)調(diào)句型的判斷
1.It was at the theatre __________ Lincoln was murdered.A.where
B.at which
C.which
D.that 2.It was the theatre _________ Lincoln was murdered.A.which
B.that
C.where
D.the one It was midnight _____ he came back.It was at midnight ____ he came back.It is in the classroom _____ we will have the test.It is the classroom _______ we will have the test.4.強(qiáng)調(diào)句型高考考點(diǎn)
1)強(qiáng)調(diào)句型與定語(yǔ)從句合用,增加試題迷惑性。他正是在入黨的那天被殺害的。
It was in Beihai Park ________ they met for the first time ________ the old couple told us their love story.A.where;that
B.that;that C.where;when
D.that;when 2)強(qiáng)調(diào)句型與賓語(yǔ)從句合用,強(qiáng)調(diào)句型 用于賓語(yǔ)從句,為一大熱門(mén)考點(diǎn)。
例如:
She looks sad.Could you please tell me ________ that prevents her from being as happy as before?
A.what it is
B.it is what
C.how it is
D.it is how Exercises 1.---Was it in 1969_____ the American astronaut succeeded_____ landing on the moon﹖
---Quite right.A.when;on
B.that;on
C.when;in
D.that;in 2.It was_____ he said _____ disappointed me.A.what;that
B.that;that
C.what;what
D.that;what 3._____ is no possibility ______ Bob can win the first prize in the match.A.There;whether
B.It;that
C.There;that
D.It;whether 4.--Where was____you picked up the wallet﹖
--Just near the school gate.A.it
B.it that
C.the place
D.the place that 5.I must find out why____so many students made the same mistake.A.is it that
B.was it which
C.it is what
D.it was that 6.__ is a fact that English is being accepted as an international language.A.There
B.It
C.That
D.This 7.Our classroom is very clean.Do you know who __ cleaned it﹖
A.was it that
B.it was that
C.was it who
D.he was 8.Is it in the factory__ you visited last week__this kind of car is made﹖
A./;that
B.where;when
C.where;that
D./;when 9.It was _____ 1920 __ regular radio broadcasts began.A.until;when
B.not until;when
C.until;that
D.not until;that 10.It is ten years ________ Miss Gao returned to China.A.that
B.when
C.since
D.as 11.It will be three years ________ we get together again.A.that
B.when
C.since
D.before 語(yǔ)法滾動(dòng)訓(xùn)練 名詞性從句
A 1.__________ has taken away my bag is unknown.2._________ breaks the law will be punished.B 1.We promise________attends the party a chance to have a photo taken with the movie star.A.who B.whom C.whoever D.whomever 2.I'm stuck on this problem;you may ask ___knows better than I.A.whoever
B.whomever
C.who
D.the one 3.To improve the quality of the products,we asked for advice from ______ had used the products.A.no matter who B.who C.anyone D.whoever C 1.________interesting the film is,I won't waste any time on it.A.No matter
B.Whatever
C.However
D.Whichever 2.If I were any younger,I would do________I am interested in.A.no matter what
B.whatever
C.no matter which
D.whichever 3.(2012·遼寧卷)The newcomer went to the library the other day and searched for_____ he could find about Mark Twain.A.wherever
B.however
C.whatever
D.whichever 4.(2012·陜西卷)As many as five courses are provided,and you are free to choose_____ suits you best.A.whatever
B.whichever
C.whenever
D.wherever 5.The how-to-book can be of help to____
wants to do the job.A.who
B.whomever
C.no matter who
D.whoever 6.wants to do the job, the how-to-book can be of help to him.A.Who
B.Whomever
C.No matter whom
D.Whoever
第五篇:高三物理大題解題技巧
高考倒計(jì)時(shí),在緊張的復(fù)習(xí)中,如何提高效率,最大化的利用有限的時(shí)間是關(guān)鍵。那么接下來(lái)給大家分享一些關(guān)于高三物理大題解題技巧,希望對(duì)大家有所幫助。
高三物理大題解題技巧
1.挖掘隱含條件
高考物理計(jì)算題之所以較難,不僅是因?yàn)槲锢磉^(guò)程復(fù)雜、多變,還由于潛在條件隱蔽、難尋,往往使考生們產(chǎn)生條件不足之感而陷入困境,這也正考查了考生思維的深刻程度.在審題過(guò)程中,必須把隱含條件充分挖掘出來(lái),這常常是解題的關(guān)鍵.有些隱含條件隱蔽得并不深,平時(shí)又經(jīng)常見(jiàn)到,挖掘起來(lái)很容易,但還有一些隱含條件隱藏較深或不常見(jiàn)到,挖掘起來(lái)就有一定的難度了。
2.重視對(duì)基本過(guò)程的分析
在高中物理中,力學(xué)部分涉及的運(yùn)動(dòng)過(guò)程有勻速直線(xiàn)運(yùn)動(dòng)、勻變速直線(xiàn)運(yùn)動(dòng)、平拋運(yùn)動(dòng)、圓周運(yùn)動(dòng)、簡(jiǎn)諧運(yùn)動(dòng)等,除了這些運(yùn)動(dòng)過(guò)程外,還有兩類(lèi)重要的過(guò)程:一類(lèi)是碰撞過(guò)程,另一類(lèi)是先變加速運(yùn)動(dòng)最終勻速運(yùn)動(dòng)的過(guò)程(如汽車(chē)以恒定功率啟動(dòng)問(wèn)題)。
熱學(xué)中的變化過(guò)程主要有等溫變化、等壓變化、等容變化、絕熱變化等。電學(xué)中的變化過(guò)程主要有電容器的充電和放電、電磁振蕩、電磁感應(yīng)中的導(dǎo)體棒做先變加速后勻速的運(yùn)動(dòng)等,而畫(huà)出這些物理過(guò)程的示意圖或畫(huà)出關(guān)鍵情境的受力分析示意圖是解析計(jì)算題的常規(guī)手段。
3.善于從復(fù)雜的情境中快速地提取有效信息
現(xiàn)在的物理試題中介紹性、描述性的語(yǔ)句相當(dāng)多,題目的信息量很大,解題時(shí)應(yīng)具備敏銳的眼光和靈活的思維,善于從復(fù)雜的情境中快速地提取有效信息,準(zhǔn)確理解題意。
4.要謹(jǐn)慎細(xì)致,謹(jǐn)防定勢(shì)思維
經(jīng)常遇到一些物理題故意多給出已知條件,或表述物理情境時(shí)精心設(shè)置一些陷阱,安排一些似是而非的判斷,以此形成干擾因素,來(lái)考查學(xué)生明辨是非的能力.這些因素的迷惑程度愈大,同學(xué)們愈容易在解題過(guò)程中犯錯(cuò)誤。
高考物理三類(lèi)熱點(diǎn)題型的總結(jié)
1.圖象題。可以說(shuō)人類(lèi)學(xué)會(huì)如何表示信息是從圖象開(kāi)始起源的,從圖畫(huà)演變出文字,進(jìn)而抽象出數(shù)學(xué)公式。看懂圖表、動(dòng)漫是從幼兒開(kāi)始的,是生活的基本能力,當(dāng)然隨著學(xué)習(xí)知識(shí)的逐漸深入,又對(duì)同學(xué)們的讀圖能力提出了更高的要求。近幾年高考圖象題的數(shù)量逐年增加,圖象表示物理問(wèn)題比文字和公式具有更大的優(yōu)越性,能形象地描述物理狀態(tài)、過(guò)程和規(guī)律,能夠把一個(gè)問(wèn)題的多個(gè)相關(guān)因素同時(shí)展現(xiàn)出來(lái),給我們分析問(wèn)題提供直觀(guān)、清晰的物理圖景,既有助于我們對(duì)相關(guān)概念、規(guī)律的理解和記憶,又有助于我們正確地把握相關(guān)物理量之間的定性、定量關(guān)系。因此要習(xí)慣用圖象表示問(wèn)題,處理數(shù)據(jù)。物理圖象不同于數(shù)學(xué)圖象的是一般兩坐標(biāo)軸表示兩個(gè)具有實(shí)際意義的物理量,首先要看清坐標(biāo)軸,理解圖象表示的是誰(shuí)隨誰(shuí)的變化,理解正、負(fù)、斜率、面積、截距、交點(diǎn)的物理意義,其次把圖形轉(zhuǎn)化為實(shí)際的物理過(guò)程,進(jìn)而理解圖象的意義并解答問(wèn)題。
2.實(shí)驗(yàn)探究題。從近幾年高考對(duì)實(shí)驗(yàn)考查的結(jié)果來(lái)看,實(shí)驗(yàn)的得分率一直很低,但實(shí)際上高考物理實(shí)驗(yàn)題目的總體難度并不高,考察的實(shí)驗(yàn)也都是考綱中明確要求的基本實(shí)驗(yàn),屬于考生最不應(yīng)該失分的題型之一。物理是以實(shí)驗(yàn)為基礎(chǔ)的學(xué)科,首先要樹(shù)立物理規(guī)律來(lái)源于實(shí)驗(yàn)、來(lái)源于生活的理念,實(shí)驗(yàn)是第一的,規(guī)律是第二的。
實(shí)驗(yàn)思想、技能和方法是高考實(shí)驗(yàn)考查的三大重點(diǎn),電學(xué)考查儀表讀數(shù)、實(shí)物圖連接、電表選取、電路設(shè)計(jì)、方案的篩選、原理的遷移、數(shù)據(jù)的處理,可以很好地考查多項(xiàng)實(shí)驗(yàn)?zāi)芰Α6骄颗c實(shí)驗(yàn)相結(jié)合使二者都具有了實(shí)際意義。每一個(gè)實(shí)驗(yàn)突出的探究環(huán)節(jié)不盡相同,關(guān)鍵是從實(shí)驗(yàn)原理出發(fā),進(jìn)行設(shè)計(jì)和變化。
3.新科技、新技術(shù)應(yīng)用題。這類(lèi)題多以當(dāng)今社會(huì)熱點(diǎn)和高新科技動(dòng)態(tài)為背景,信息量一般較大、題干較長(zhǎng),一般是描述一種裝置或某一理論的基本精神,再和中學(xué)物理知識(shí)連接。表面看來(lái)給人一種很復(fù)雜的感覺(jué),但抽象出物理模型時(shí)就會(huì)有一種“現(xiàn)象大、問(wèn)題小”的轉(zhuǎn)折。要求學(xué)生在考場(chǎng)上對(duì)新情景新信息完成現(xiàn)場(chǎng)學(xué)習(xí),將信息進(jìn)行有效提煉、加工、建模,與原有知識(shí)銜接來(lái)解決問(wèn)題。這類(lèi)問(wèn)題不僅對(duì)學(xué)生的創(chuàng)新能力是一個(gè)考查,而且對(duì)學(xué)生的心理素質(zhì)也是一個(gè)考驗(yàn)。
高三物理大題答題方法
1.規(guī)范答題格式
做物理大題時(shí),要慢審題快答題,有些學(xué)生題目還沒(méi)有看清楚就急著答題,既浪費(fèi)了時(shí)間又失了分。大題中包括實(shí)驗(yàn)題和計(jì)算題,作答時(shí)一定要按照各科的具體特點(diǎn)和要求規(guī)范書(shū)寫(xiě),對(duì)于一些文字?jǐn)⑹龅拇鸢福瑢?xiě)完后要讀一下,看是否符合邏輯關(guān)系,是否簡(jiǎn)潔明了。
2.認(rèn)真審題,不見(jiàn)句號(hào)不答題
審題時(shí)一定要通讀全題,審出題干中的關(guān)鍵詞和隱含的信息,準(zhǔn)確找出答題的突破口和限制性條件。見(jiàn)到熟悉的內(nèi)容和題型,不要盲目樂(lè)觀(guān),因?yàn)樵诟呖荚囶}中有原題的可能性很小,往往是材料熟悉,但出題的角度、方式會(huì)有很大變化,一定要認(rèn)真分析,不要受原題的干擾,以避免失分;見(jiàn)到新題、難題,不要過(guò)分緊張,因?yàn)檫@些題對(duì)所有考生來(lái)說(shuō)都新、都難,要相信材料再新,所考查的知識(shí)肯定是我們學(xué)過(guò)的,不要被新信息所蒙蔽。