问题 选择题

传感器是一种采集信息的重要器件.如图是一种测定压力的电容式传感器.当待测压力F作用于可动膜片电极上时,可使膜片产生形变,引起电容的变化,将电容器、灵敏电流计和电源串联接成闭合电路.那么(  )

A.当F向上压膜片电极时,电容将减小

B.当F向上压膜片电极时,电容不会改变

C.若电流计有示数,则压力F不发生变化

D.若电流计有示数,则压力F发生变化

答案

答案:D

题目分析:由平行板电容器的公式知当F向上压膜片电极时,d变小,电容C将增大,AB错;若电流计有示数,说明电容在变化,即d在变化,则压力F发生变化,C错,D对。

点评:本题学生明确电容发生变化后,其电荷量发生变化,所以电容器要进行充放电,在电路中就有电流存在。

阅读理解

There is a new park near Andy’s home. It’s fine today. Andy and his family are in the park now. On their left, there is a café. On their right, there is a big lake. There are many flowers and trees around the lake. There’s a small hill behind the lake. Near the lake, there are two signs. One says, “Don’t swim in the lake!” The other says, “No fishing!” But you can go boating on the lake. There is a beautiful garden in the middle of the park. There are green grass and beautiful flowers in it. There are some small shops between the lake and the garden. The park is so nice. Andy and his family like it very much.

(   )11. The park near Andy’s home is ____________.      .

A. new and beautiful    B. old and beautiful   C. clean and new   D. old and clean

(   )12. Is there a café in the park? ---_____________.      

A. Yes, there isn’t.      B. No, there isn’t.   C. Yes, there is.    D. No, there is.

(  )13. People can________ on the lake.

A. swim                 B. fish                C. boat              D. play

(   )14. The shops in the park are not _____________.      .

A. small                  B. big                 C. good            D. pretty

(   )15. Do Andy and his family like the park?  --__________.    

A. Yes, they don’t.                      B. No, they do.      

C. Yes, very much.                    D. No, they don’t.

单项选择题