问题 选择题

下面关于杠杆的说法.正确的是( )

A.硬的直棒就是杠杆;

B.等臂杠杆既不省力也不费力;

C.费力杠杆的动力臂比阻力臂长;

D.从支点到阻力作用点的连线叫阻力臂。

答案

答案:B

能绕固定点转动的硬棒叫做杠杆,跟外形没有关系。等臂杠杆等力。费力杠杆阻力臂大于动力臂。从支点到阻力的距离叫做阻力臂。

完形填空

根据短文,把下列句子补充完整。(5分)

One day , Mrs.Wilson took Tracy and Aben shopping . They went to the supermarket in the new shopping center .

“ Why do you buy things here ?” Tracy wanted to know .

“ Because it is cheaper here than the store on the corner ,” Mrs.Wilson said . “ Help me check the price .”

The Wilsons were not rich , so Mrs.Wilson was always careful with her money . She looked carefully at the prices of things .

She bought a lot of things in the supermarket . When they got home , the children said , “We don’t think you saved any money by going to the supermarket .”

“ Of course , I did ,” Mrs.Wilson said , “ Everything was cheaper there .”

“ We know ,”the children said , “But we came home by taxi because we had too much to carry .The taxi fare was more than the money that you saved !”

Mrs.Wilson added everything up . Her children were right .

“ Well done ,” she said . “ Next time we’ll do our shopping near our home .”

小题1:Mrs.Wilson went to the supermarket to _______ things because they are ________ there .

小题2: Mrs.Wilson was always _________ with her money because the Wilsons were ________ .

小题3: Mrs.Wilson’s ______ helped her check the ________ when they were in the supermarket .

小题4: After they did some shopping , Mrs.Wilson and her children went home ______ _______.

小题5: The Wilsons couldn’t walk home because it was too _______ away from the supermarket to their home , and they had too __________ things .

单项选择题