第一篇：八年級英語下冊第八單元練習題1大全

八年級下冊第八單元練習題

一．單項選擇。

()1.What should I get my mom _______ her birthday?

A.forB.onC.atD.in

()2.Why don't you ______ a camera? That’s too cheap.A.gotB.getC.getsD.getting

()3.What’s the best gift John ____ ever received?

A.haveB.hasC.hadD.having

()4.Why ______him clean the classroom?

A.not you helpB.don’t helpC.not helpD.not helping

()5.Mrs Green is a ___________ woman.A.30 yearsB.30 yearC.30-year-old D.30-years-old

()6.Goldfish are easy _______________.A.look after B take care C to looking after D to take care of

()7.The girl was too young _________ to school.A.not to goB to goC for goD to going

()8.Peter spends lots of time _________books.A.looking atB onreadC in seeingD reading

()9.Please remember _____off the light before you leave.A.turnB turningC to turnD to get

()10.Every day I have enough time _____ my dog.A play withB playing andC to play withD to play

二．用所給詞的正確形式填空。

1．I went shopping instead of________TV at home.(watch)

2．There are some_____ in the house.(mouse)

3．That machine is making a ______(noisy)

4．We _________ any classes next week.(not have)

5.He wants to buy a______car.(person)

6．That book is _______enough.(interest)

三．根據(jù)提示，把下列的句子翻譯成英語。

1.鸚鵡是最不尋常的動物。

______ are ___________________ pets.2.這些天來最流行的寵物是大肚豬。

The ______ kind of pet _____________ is the ______ pig.3.Tom養(yǎng)了一只叫做Connie的烏龜.Tom has a _____________ Connie.4.這些書將會被贈送給孩子們。

These books will _________________ to children.5.電影太無聊了，演了一半我就睡著了。

初中英語

八年級英語 1

The movie was too broing.I ___________ half way through it.四． 把下列各句重新排列，使之成為一段通順的對話

A.Mm.I have no idea...OK, some flowers!Give her some flowers with best wishes.I think they’ re the best gifts for her!

B.The day after tomorrow is my mother’ s birthday.What should I get her?

C.Yeah!Good idea!I will help her finish housework and then give her the beautiful flowers!

D.Does she like little animals? Why don’ t you get her a pet cat?

E.No way.It’ s too expensive and I haven’ t enough money to buy it.F.Great!I think your mother will happy to receive your gift.G.No, she doesn’t like them at all.H.Yes, I’d love to.I.What about a camera? I think it’ s a nice gift for your mother.J.Thank you!Will you go and buy the flowers with me?

1.______2.______3.______4.______5.______

6.______7.______8.______9.______10.______

五．閱讀理解。

(一)In almost every big university in the United States football is a favorite sport.American football is not like soccer.Players sometimes kick the ball, but they also throw the ball and run with it.They try to take it to the other end of the field.They have four chances to move the ball ten yards.They can carry it or throw it.If they move it to the end of the field, they receive six points.This is called a touch—down.It is difficult to move the ball.Eleven men on the team try to stop the man who has the ball.If the man does not move the ball ten yards, his team kicks the ball to the other team.Each university wants its team to win.Thousands of people come to watch.They all yell for their favorite team.Young men and women called cheerleaders come on the field to help the people yell more.They dance and jump while they yell.Each team plays ten or eleven games each season.The season begins in September and ends in November.If a team is very good, it may play another game after the season ends.The best teams play again on January 1st, the first day of the New Year.Many people go to see these games and many others watch them on television.()1.In American football players can ___.A．only kick the ball

B．only throw the ball

C．only carry the ball

D．kick, throw and carry the ball

()2.If a team wants to get points, it has to move the ball ___.A.10 yardsB.to the other end

C.40 yardsD.away from its own end

()3.Who are dancing and jumping while they yell?

A．The cheerleaders.B．All those who are watching the game.C．The winners.D．The players of both sides.()4.Most teams play games in ___.A.springB.summer

C.autumnD.winter

()5.When do the best teams play again?

A.At Christmas.B.Before the season ends.C.On New Year’s DayD.On the last day of season

(二)仔細閱讀下面的文章，然后選擇正確答案

Our eating habits are very important for good health and a strong body.There are times when most of us like eating sweets and ice cream better than meat and rice.Sweets and ice cream are not bad for us if we eat them at the end of a meal.If we eat them before a meal, they may take away our appetite(食欲).It’s important for us to eat our meal at regular(規(guī)律)time each day.When we feel worry or excited, we may not want to eat.A long time ago, in England, some judges often decided whether a man was telling truth by giving him some dry bread.If the man could not swallow(吞)the bread, it meant that he wasn’t telling the truth.Though this seems strange and foolish they thought it was good way of finding out truth.A man who is worrying something has difficulty in swallowing anything dry, because he loses his appetite.()1.Good eating habits make us ________.A.strongerB.happier

C.more beautifulD.more polite

()2.It’s good to eat sweets and ice cream ________.A.after a mealB.before a meal

C.when we are happyD.when we want to eat

()3.It’s good for us to have our meal ________ every day.A.earlierB.at the same time

C.at any timeD.at the different time

()4.The judge in old England thought if a man didn’t tell me the truth, he can ________.A.drink milk or teaB.eat a lot of dry bread

C.hardly eat dry breadD.swallow dry bread easily

七．書面表達

明天是媽媽的生日，你和爸爸商量給媽媽買什么做禮物，編一段對話。

以下詞匯可供參考。

creative enoughpay forgive awayenough money

第二篇：英語八年級下冊第八單元總結(jié)

Unit 8 why don’t you get her a scarf ?

1.表示建議的句型

Why don’t you do sth? =why not do sth? 8.what a lucky guy he is!=how lucky the guy is!How about sth?=what about sth? Shall we do sth? Let’s do sth?

Would you like to do sth? 表同意:Good idea.Sounds good.I agree with you.Why not? I think so.表否定： I disagree with you.Bad idea.I don’t think so.2.buy sth for sb=buy sb sth=get sb sth 3.adj.+enoughenough+n.4.give sb sth =give sth to sb 5.not creative enough 不夠創(chuàng)新 6.gift giving

7.instead of+doing /n./pron.Instead放詞尾 9.Receive 收到 是客觀上的 Accept 接受 是主觀上的 10.learn doing/ to do sth 11.try on 試穿

12.比較級+than +any other+n.任何一個都）

13.One of +the +最高級+n復數(shù) 14.Run out of

15.From across china=from all over china 16.Encourage sb to do sth 鼓勵某人做某事 17.Take/have an interest in=be interested in 18.Make much/great progress by doing sth通過做某事取得巨大進步

19.rather than而不是,與其……不如……。可作為一個連詞詞組,用來連接兩個并列成分,表示在兩者中進行選擇,意為“是A而不是B”,“要A不要B”,“寧愿A而不愿B”。后面可以接名詞、名詞短語、代詞、形容詞、副詞、動詞、不定式、動名詞等

第三篇：人教版八年級英語下冊教案第八單元

全國中考信息資源門戶網(wǎng)站 www.tmdps.cn

Unit8 Why don’t you get her a scarf?

全國中考信息資源門戶網(wǎng)站 www.tmdps.cn

全國中考信息資源門戶網(wǎng)站 www.tmdps.cn

全國中考信息資源門戶網(wǎng)站 www.tmdps.cn

全國中考信息資源門戶網(wǎng)站 www.tmdps.cn

全國中考信息資源門戶網(wǎng)站 www.tmdps.cn

全國中考信息資源門戶網(wǎng)站 www.tmdps.cn

全國中考信息資源門戶網(wǎng)站 www.tmdps.cn

全國中考信息資源門戶網(wǎng)站 www.tmdps.cn

全國中考信息資源門戶網(wǎng)站 www.tmdps.cn

第四篇：2013年人教版七年級英語下冊第八單元練習題pi

由蓮山課件提供http:///資源全部免費

2012年版七年級英語下冊Unit 8單元測試

Section A

1.根據(jù)句意及首字母提示完成單詞

1.2.3.4.5.Can you go to the p_________ office to send a letter for me? Tom is ill in h_________.Let’s go to the r__________ and eat some food.We often buy a lot of things in the s__________ on Sundays.You should put the money in the b_______.2.從括號中選擇恰當?shù)慕樵~填空

（between, to, from, on, of）xK b1.Co m

1.The library is across _______ my home.2.Tuesday is ________ Monday and Wednesday.3.Is the hospital next _______ the park or far ________ it?

4.The restaurant is ________ the other side of the street.5.The supermarket is in front ________ the school.3.單項選擇

1.Can you swim _______ the river?()

A.nearB.betweenC.fromD.across

2.________ , where is the park?()

A.HiB.HelloC.Excuse meD.Excuse

3.The hotel is ______ the bank.()

A.acrossB.fromC.across formD.next 新 課標第一 網(wǎng)

4.We ______ a big family.()

A.areB.haveC.hasD.there are

5.There isn’t a restaurant ______ here.()

A.inB.nearC.fromD.on

6.----Thank you very much..()

----____________

A.You’re welcome.B.Really?

C.Nice to meet you.D.Thank you,too.7.----Is there a library in your school?()

----___________.A.Yes,it is.B.No,it isn’t.C.Yes,there is.D.No,there aren’t.8.----_______ is the park?()

----It’s on the right of the school.A.WhereB.WhatC.WhyD.How

9._______ any books on the desk?()X|k | B| 1.c|O |m

A.There isB.There areC.Is thereD.Are there

10._________ something wrong with my bike.Can I use yours?()

A.It isB.It wasC.There isD.There was

4.句型轉(zhuǎn)換 對劃線部分提問)

________ ________ near the library?

由蓮山課件提供http:///資源全部免費

2.There is a pay phone near the school.(改為一般疑問句)

________ ________ a pay phone near the shool? 對劃線部分提問)

____________ the hotel?

4.There is a pen in my pencil case.(改為同義句)

I ________ a pen in my pencil case.5.閱讀理解

Johnson likes swimming in a small river near his house.But then his father goes to work in a big city and Johnson goes with his family.Their new house has a garden ,but the garden is very small Johnson is not very happy.“Is there a river near the house ?”he askes his father on the first morning.” No, there isn’t.But there is a big park near here.And there’s a pool in it.“ “We are going there this afternoon.“says his father.Johnson is happy.新|課 | 標|第|一| 網(wǎng)

Johnson and his father go to the park in the afternoon.Johnson wants to walk near the pool.Ut he sees a sign.His father reads it to him: “Warning : This pool is dangerous.365 people fell into it.“Johanson looks into the pool carefully , then he says ,”I can’t see them.()1.There is a _______ near Johnson’s new house.A.small riverB.big parkC.small gardenD.big pool

()2.John isn’t very happy because __________.A.there isn’t a big park

B.there’s a pool

C.his father goes to work in a big city

D.there isn’t a river near the newhouse.()3.There is a _______ near the pool.A.signB.riverC.gardenD.tree

()4.The warning tells people ________ near the pool.A to look into itB.not to swim

C.to be carefulD.not to look into it

()5.Which isn’t right ?

A.There isn’t a small river near Johnson’s house.B.Johnson’s father gets a new job in a big city.C.Johanson is afraid to walk near the pool

D.Johnson goes to the big city with his father.Section B

1.單項填空

1.My sister enjoys________the guitar in the park every morning.A.playB.playsC.playingD.to play2、there is a beautiful garden ________fifthavenue（A．onB．inC．a(chǎn)tD．with

3.I want to find a house __________ many trees around it.X k B1.c o m

A.withB.haveC.hasD.there are

4.Go ________this sereet and then turn right..A.FromB.toC.downD.on

5.There______some water in the glass.A.isB.areC.beD.has

6.Alice spends too much time _______computer games.A.playB.playsC.to playD.playing

7.Go straight and turn ______.The bank is ______.A.left;leftB.left;on the leftC.on the leftD.left;to left

8.My father has a habit of jogging _______the Jinchuan River for an hour in the morning,A.betweenB.alongC.overD.through

9.Julia ______a bus to work every day,A.bringsB.hasC.getsD.takes

10.I hope you ______a good time.A.to haveB.haveC.hasD.having

2.用所給單詞的適當形式填空

1.The children enjoy _______（play）soccer after class.新 課標第一 網(wǎng)

2.She ______（go）home at five every afternoon.3.I spend much time _______(speak)English every morning,4.I can find the hotel ________(easy).5.You should turn right at the second ______(cross).6.I think money ________(be not)everything.7.I love to watch monkeys _______(climb)trees.8.There _______(be)a pen and two pencils in the box.3.根據(jù)漢語意思完成句子

1.沿著第五大街走，然后左轉(zhuǎn)。

Go____Fifth Street,then_____________,2.我家在一條喧鬧的大街上。

My house is ______a noisy ________.3.從機場坐出租車，沿著公路走，直到看到一個圖書館在你的右邊。

_______________________ from the airport and _______________ the road until you see a library ___________________________

4.沿著這條街走。你能很容易地到達圖書館。

_________________.You can get to the library _______.5.請在第一個十字路口處向右拐。

Please ________________ at the first _________.4.完形填空

Mike is an Englishman.He lives in a __1___ building in the __2___ London.There are eighteen floors in the building and he lives on the fifteenth floor.He__3___ a lift(電梯)to go up and down.He works very hard.He__4___ to work early.Every day he leaves his__5__and walks to the lift.He gets into the lift.It __6___him down to the first floor.He gets out of the lift.Then he walks to __7___bus stop.The bus stop is in front of a station.It is about two hundred meters from ___8___home.Usually, he catches the number 11 bus to work, but sometimes he goes__9___.He works in a factory about ten__10___ from his home.His work starts at half past eight, and finishes at a quarter to five.He gets back home at half past5.X k B1.c o m

（）1.A.tall B.shot C.small D.large

（）2.A.country B.town C.city D.village

（）3.A.makes B.uses C.does D.mends

（）4.A.begins B.wants C.runs D.goes

（）5.A.home B.building C.office D.room

（）6.A.costs B.spends C.takes D.brings

（）7.A.an B.a C.the D./

（）8.A.his B.he C.him D.himself

（）9.A.by plane B.by train C.on foot D.by air

()10.A.meters B.kilometers C.minutes D.hours

Self Check 新|課 | 標|第|一| 網(wǎng)

1.任務型閱讀

It was the last day of the winter vacation.Li Xin went to bed early in the evening.He wanted to go to school early the next morning because he couldn?t wait to see his teachers and classmates.The next morning, Li Xin got up at 6:00.He looked“Wow, how beautiful!” said Li Xin.There were many trees in front of his house.They were really beautiful with the white snow.He went out of his house and was going to school.How did Li Xin go to school? There was much snow on the street.He decided to walk to school.Twenty minutes later,Li Xin got to school.Some teachers and students were cleaning the snow outside the classrooms Li Xin did it,too.He was tired ,but he felt happy on the first dayback to school.1.判斷正誤 Li Xin went to bed early on the evening of the first school day.()

2.補全句子Li Xin wanted to go to school early because_______________________________

3.What were in front ofLi Xin’shouse.?回答問題_______________________________

4.How did Li Xin go to school? 回 答 問 題 _______________________________

5.將劃線句子翻譯漢語 ____________________________________。

2.完形填空

This is my bedroom.I can see _1_ pictures on the wall.The light is _2_ the desk.The football is _3_ the chair._4_ is the bed? It's near the table.My father and _5_ bedroom is near my bedroom._6_ flowers and a bed _7_ in their room.Some windows are _8_ the wall.A yellow door is in the wall, _9_.I like my bedroom and they like _10_.1.A.aB.oneC.anD.some（）

2.A.underB.onC.inD.behind（）

3.A.onB.underC.toD.for（）

4.A.WhoB.WhatC.WhichD.Where（）

5.A.sisterB.motherC.mother'sD.sisters（）

6.A.TheB.theC.SomeD.some（）

7.A.isB.areC.isn'tD.am（）X k B1.c o m

8.A.onB.behindC.inD.under（）

9.A.alsoB.thereC.hereD.too（）

10.A.alsoB.theirs'C.themD.their room（）

3.書面表達

假如你叫Mike,你的朋友Larry明天要到你所在的城市，但是你沒有時間去機場接他。請給他發(fā)一封電子郵件，告訴他怎樣從機場到你家。要求包括下面的要點，不少于50詞。開頭和結(jié)尾已給出，不計入總次數(shù)。

要點提示：

1.先乘出租車從機場到和平路。

2.沿著和平路走，經(jīng)過一家超市向右拐。

3.穿過第八大街，當看到一個郵局時，向右拐。能看見一座紅色的房子，那就是我的家。X k B1.c o m

Dear Larry,I know you are arriving tomorrow.But I am sorry that …

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________I hope you have a good trip.Yours,Mike

新課標第一網(wǎng)系列資料

第五篇：2018-2018八年級物理第八單元同步練習題

2018-2018八年級物理第八單元同步練習題

為了能幫助廣大學生朋友們提高成績和思維能力，查字典物理網(wǎng)初中頻道特地為大家整理了八年級物理第八單元同步練習題，希望能夠切實的幫到大家，同時祝大家學業(yè)進步!

一、選擇題(共18小題，每小題只有一個符合題意的選項，請將這個選項前的字母代號用2B鉛筆在答題卡上填涂。每小題2分，計36分)

1.如圖所示為小麗向右推墻的情境，下列分析正確的是

A.她推墻時，墻對她沒有作用力

B.她推墻后向左運動，離開墻后繼續(xù)向左運動，是因為受到墻的推力作用

C.她滑行一段距離后會停下來，是因為受到平衡力的作用

D.她靜止在水平地面上時，受到的重力與地面對她的支持力是一對平衡力

2.下列有關(guān)力的說法正確的是

A.摩擦力是一種總是阻礙物體運動的力

B.物體所受重力的方向始終豎直向下

C.兩個物體只有接觸才能產(chǎn)生力的作用

D.物體只有漂在液面上才會受到浮力的作用

3.如圖所示，關(guān)于力的作用效果的說法中，錯誤的是

A.魚線對魚竿的拉力使釣魚竿發(fā)生形變

B.瓶對海綿的壓力使海綿發(fā)生形變

C.球拍對乒乓球的作用力改變了乒乓球的運動方向

D.腳用力踢足球時，能使足球飛出去，說明力是維持物體運動的原因 4.下列有關(guān)于運動和力的說法中正確的是

A.給正在運動的物體再施加一個力，物體一定比原來運動得更快

B.運動的物體如果不受外力的作用時將會慢慢停下來

C.推出去的鉛球繼續(xù)前進是因為受到了慣性的作用

D.跳傘運動員在空中勻速下降時機械能逐漸減小

5.當懸掛在教室的電燈靜止時，下列說法正確的是

A.電燈對電線的拉力與電線對電燈的拉力是一對相互作用力

B.電燈對電線的拉力與電線對電燈的拉力是一對平衡力

C.電燈對電線的拉力與電燈受到的重力是一對平衡力

D.電燈對電線的拉力與電燈受到的重力是一對相互作用力 6.下列現(xiàn)象中，不能用慣性知識解釋的是

A.司機開車時需要系安全帶 B.運動員跳遠時需要助跑

C.騎自行車時為了減速捏緊車閘 D.投出去的鉛球離開手后繼續(xù)向前運動

7.如圖所示的實例中，為了減小摩擦是

A.旱冰鞋上的滑輪 B.運動鞋底上的花紋 C.浴室腳墊上的顆粒 D.雪天輪胎上繞的鏈條

8.5月30日，2014年屈原故里端午文化節(jié)開幕式暨傳統(tǒng)龍舟賽在秭歸隆重舉行，使龍舟向前行駛的力的施力物體是

A.船槳 B.龍舟 C.舟上選手的手臂 D.江水

9.下列關(guān)于力學現(xiàn)象的解釋中正確的是

A.人用力推車，車未動，是因為推力小于摩擦阻力

B.蘋果在空中下落得越來越快，是因為力是改變物體運動狀態(tài)的原因

C.汽車剎車后，速度會逐漸減小，最后會停下來，是因為汽車具有慣性

D.書本靜止在課桌上，是因為書本受到的重力與書本對桌面的壓力平衡

10.如圖所示，小葉觀察家中的平底茶杯放在水平桌面時的情形時想：如果將空茶杯正放在桌面上對桌面的壓力和壓強分別為F1和P1，再將它倒扣在同一桌面上對桌面的壓力和壓強分別為F2和P2，那么F1與F2和P1與P2間的關(guān)系正確的是

A.F1 P1=P2 B.F1=F2 P1 C.F1

11.2014年4月28至29日的兩天里，31場龍卷風連日襲擊美國中南部6周，龍卷風的實質(zhì)是高速旋轉(zhuǎn)的氣流，它能把地面上的物體或人吸起卷入空中，龍卷風能吸起物體的主要原因是

A.龍卷風增大了空氣對物體的浮力 B.龍卷風中心區(qū)域的氣壓遠小于外部的氣壓

C.龍卷風使物體受到的重力減小 D.龍卷風產(chǎn)生了強大的萬有引力將物體吸上天空

12.下列有關(guān)做功的說法正確的是

A.用水平力推著購物車前進，推車的力做了功

B.把水桶從地面上提起來，提水桶的力沒有做功

C.書靜止在水平桌面上，書受到的支持力做了功

D.掛鉤上的書包靜止時，書包受到的拉力做了功

13.下面是日常生活中與壓強有關(guān)事例的描述，其中正確的是

A.圖釘帽面積大是為了增大手指對它的壓強

B.水電站的攔河壩設(shè)計成上窄下寬是因為液體的壓強隨著液體深度的增加而增大

C.用吸管吸飲料是利用了嘴的吸力

D.高壓鍋能很快地煮熟食物是對大氣壓的利用

14.端午節(jié)那天，小明發(fā)現(xiàn)煮熟的咸鴨蛋甲漂浮在水面，乙沉在水底，如圖所示。若甲的體積比乙小，則下列分析合理的是

A.甲的質(zhì)量比乙大 B.甲受到的浮力等于甲的重力

C.甲的密度比乙大 D.乙受到的浮力大于重力

15.三位同學準備進行爬樓比賽，看看誰的功率大。比賽前他們展開了如下的討論：

甲：只有測出各自的體重、爬樓用的時間和爬樓的長度，才能進行比較

乙：在爬樓的時間相同時，只要測出各自的體重、爬樓的高度，就可以進行比較 丙：在爬樓的高度相同時，只要測出各自的體重、爬樓的時間，就可以進行比較

A.甲、乙、丙 B.甲、乙 C.甲、丙 D.乙、丙

16.圖所示的工具中屬于費力杠桿的一組是

A.①② B.②③ C.②④ D.③④

17.一個滑輪組經(jīng)改進后提高了機械效率，用它將同一物體勻速提升相同的高度，改進后與改進前相比

A.有用功減少，總功減少 B.有用功增加，總功增加

C.有用功不變，總功不變 D.有用功不變，總功減少

18.如圖所示，小華把懸掛的鐵鎖拉近并緊貼自己的鼻子，穩(wěn)定后松手，頭保持不動，鐵鎖向前擺去又擺回。下列說法正確的是

A.鎖不斷地來回擺動，是因為動能不斷增加 B.鎖向下擺的過程中，重力勢能轉(zhuǎn)化為動能

C.鎖擺到最低點后會繼續(xù)上升，是因為受到重力作用

D.鎖擺動的過程中，擺回來時有可能會碰到鼻子

二、填空題(共7小題，每小題2分，計14分)

19.如圖是天宮一號飛行器運行軌道的示意圖;若它沿橢圓軌道繞地運行的過程中機械能守恒，則它從遠地點向近地點運行的過程中動能，機械能(均選填增大、減小或不變)

20.小強用10N的水平推力勻速推動放在水平地面的課桌，則課桌受到地面對它的摩擦力大小為 N;某同學將該課桌內(nèi)的書包拿走后，把課桌沿原路用水平力推回的過程中，課桌受到地面對它的摩擦力。(選填增大、減小或不變)

21.一個豎直懸掛在水中的圓柱體，上表面受到水的壓力是5N，下表面受到水的壓力是13N，那么這個圓柱體受到水的浮力大小是 N，方向是。

22.某校在對學生開展安全教育實踐活動中，利用如圖的圖片告知學生無論汽車落水還是遇雨被淹，都應立刻開門逃生，越遲疑車門越難推開，因為車輛被淹越深，車門下部O處受到水的壓強越。緊急情況下，應揮動逃生錘的B端砸向玻璃窗的邊角，破窗逃離，因為B端比A端，更容易砸破玻璃窗。

23.如圖所示，A、B是兩個上端開口的容器，它們構(gòu)成的是一個當用一個管子沿B容器口吹氣時，B容器中的液面會。(填上升下降或不變)

24.潛水艇能夠上浮和下沉是通過改變 來實現(xiàn)的;潛水艇在上浮的過程中，未露出水面之前，所受的浮力將。(選填變大、變小或不變)

25.升降式晾衣架結(jié)構(gòu)如圖所示，它們實際上是一組簡單機械，由固定在墻壁和天花板上的定滑輪和升降鋼索的轉(zhuǎn)動搖把組成，可以省了的是，可以改變力的方向的是。

三、實驗與探究(第26小題2分，第27、28小題各4分，第29小題5分，計15分)

26.如圖所示，課桌的重心在O點，若在課桌的C電用力F把桌腿B抬離地面，在抬起時另一桌腿A沒有滑動，請在圖中畫出力F相對于A點的力臂L1和課桌重力G的示意圖。

27.小偉在探究影響滑動摩擦力大小的因素的實驗中，他猜想影響滑動摩擦力的大小因素可能用：①接觸面所受的壓力大小;②接觸面的粗糙程度;③接觸面積的大小。接著小偉就通過如圖13所示的實驗來驗證他的猜想：

(1)實驗中小偉用彈簧測力計水平勻速直線拉動木塊在長木板上滑動，這樣做是為了利用 的原理得出拉力等于摩擦力，從而測出木塊所受摩擦力的大小。

(2)如果小偉要探究猜想②，他應該選擇 兩幅圖所示的實驗步驟來操作，根據(jù)圖中彈簧測力計的示數(shù)可得出結(jié)論：在壓力和接觸面積相同的情況下，滑動摩擦力越大。

(3)小偉要探究猜想③，他將木塊切去一半，重復甲的操作過程，如圖丁所示。它比較甲和丁的實驗結(jié)果，得出結(jié)論：滑動摩擦力的大小與接觸面積的大小有關(guān)。那么小偉在實驗中存在的問題是。

28.如圖為小敏同學探究杠桿平衡條件的實驗裝置。

(1)試驗時，小敏同學先調(diào)節(jié)平衡螺母，使杠桿在水平位置平衡，是為了，通過多次實驗，小敏同學得到了用字母表示的杠桿的平衡條件是。

(2)實驗中，在杠桿上的A電掛四個重均為0.5N的鉤碼，用調(diào)好的彈簧測力計豎直向上拉杠桿上的B點，使杠桿水平平衡，如圖14所示，則測力計的示數(shù)應該是 N;如果將測力計沿圖中虛線方向拉，仍使杠桿在水平位置平衡，則測力計的示數(shù)將。(填變大、不變或變小)

29.小明同學在探究影響浮力大小的因素時，做了如圖所示的實驗，請你根據(jù)小明的實驗探究回答下列問題。(水=1.0103kg/m3)

(1)根據(jù)圖中所標的實驗數(shù)據(jù)，可知物體浸沒在鹽水中所受的浮力是 N。

(2)根據(jù)圖C與圖E的實驗數(shù)據(jù)，可得出實驗結(jié)論是：。

(3)根據(jù)ABCD四個圖中的實驗數(shù)據(jù)，還可以發(fā)現(xiàn)當物體浸入同種液體時，物體所受浮力的大小與 有關(guān)，與 無關(guān)。

(4)根據(jù)有關(guān)實驗數(shù)據(jù)，可以計算出鹽水的密度為 kg/m3。

四、應用與實踐(共3小題，第30小題4分，第31小題5分，第32小題6分，計15分)

30.如圖所示為小明做俯臥撐的示意圖，若把他的身體看做一個杠桿，O為支點，A為重心，他的體重為550N，求：

(1)地面對手的支持力F的大小是多牛?

(2)當他將雙手撐地改為單手撐地后，他對地面的壓強將如何變化?并說明理由。

船名中國海監(jiān)5001

型號船長88m型寬12m型深5.6m

滿載排水量1500t

巡航速度36km/h 31.2013年6月1日，由武漢造船廠制造的中國海監(jiān)5001在江蘇南通交付使用，它是目前我國最先進的海洋公務執(zhí)法船。其部分技術(shù)參數(shù)如下表(海水密度海水=1.0103kg/m3)。求：

(1)海監(jiān)船由長江駛?cè)氪蠛?zhí)行任務時，船體會 一些。(填上浮或下沉)

(2)海監(jiān)船在某海域巡航時，船底在海水中的深度達到3.0m，求船底受到海水的壓強是多少帕?

(3)海監(jiān)船滿載時受到的浮力是多少牛?

32.2014年2月25日宜昌BRT快速公交項目工程建設(shè)正式啟動，工程施工中使用了如圖18甲所示的某型號挖掘機運送沙土，該型號的挖掘機空載時的總質(zhì)量是9t,每條履帶與地面的接觸面積是2.25㎡。在運送沙土中，它將裝有1.8104N沙土的鏟斗用4s的時間以2.4m/s的平均速度從圖18乙中最低點A移送到最高點B，接著再用2s的時間沿水平方向移動4m將沙土卸到汽車上。求：

(1)挖掘機靜止、空載且不工作時(如圖甲所示)對水平地面的壓強是多少帕?

(2)挖掘機在運送1.8104N沙土中對沙土做了多少焦耳的功?

(3)如果挖掘機在上述運送沙土過程中的平均功率為60kw，此過程挖掘機的機械效率是多少?

一、選擇題(共36分，每小題2分)

題號******8

答案DBDDACADBDBABBDCDB

二、填空題(共14分，每空1分)

19.增大 不變 20.10 減小

21.8 豎直向上 22.大 受力面積小，壓強大

23.連通器 上升 24.自身的重力 不變

25.轉(zhuǎn)動搖把 定滑輪

三、實驗探究題(第26題2分，第27題4分，第28題4分，第29題5分，計15分)

26.評分說明：正確畫出F 的力臂L1(1 分)、重力G的示意圖(1 分)

27、(1)二力平衡;

(2)甲和丙 接觸面越粗糙;

(3)沒有控制壓力大小保持不變

28、(1)讓力臂沿杠桿，便于直接從杠桿上讀出力臂的大小;F1L1= F2

(2)1 變大