如图所示是一些日常生活中所使用的机械或工具，其中属于省力杠杆

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问题选择题

如图所示是一些日常生活中所使用的机械或工具，其中属于省力杠杆的是（　　）

A．

B．

C．

D．

答案

我们在使用羊角锤时是为了省力，并且在使用的过程中动力臂大于阻力臂，所以它是省力杠杆；

而在使用筷子、钓鱼竿和铁锨时，都是动力臂小于阻力臂，所以它们都是费力杠杆，费力但省距离．
故选B．

填空题

用括号中所给词的适当形式填空。

New Year's Resolution Survey Results

We got over 1,000 letters, 1._____ (fax), and e-mails from our readers about their New Year's

resolutions. Thank you! Many readers are 2._____ (go) to work harder in school this year. Lots of

readers are going to play 3._____ (sports). Some readers said they are going to eat 4._____ (many)

vegetables. A few readers said they are going to learn a new language. Some girls 5._____ (say) they

are going to exercise more to keep fit. Some parents are going to study the subjects their 6._____ (child)

learn at school. They want to communicate 7._____ (good)with their kids. An old lady said she found a

job as a foreign language teacher. She is going to look for a 8._____ (teach) job in China next year.

单项选择题

下列属于条件反射活动的是（）

A.看到酸梅时引起唾液分泌

B.食物进入口腔后，引起胃腺分泌

C.大量饮水后尿量增加

D.寒冷环境下皮肤血管收缩

E.炎热环境下出汗