问题 选择题
求如图所示的交变电流的有效值,其中每个周期的后半周期的图象为半个周期的正弦曲线(   )

A.5A

B.5A

C.5/2A

D./2A

答案

答案:C

阅读理解

阅读理解

                                              Just Around the Corner

       I have a friend named Jim.  He lived just around the corner from me,  The days go by, and before

I know it, a year is gone.  I never see my old friend's face.  He knows that I miss him too,  as I used to

ring his bell,  and he rang mine,  in the old days.   If  we were younger, things might be different, but now, we are busy, tired men.  We are even tired of playing games.

       "Tomorrow," I said to myself, "I will call on Jim just to show that I'm thinking of him. " But tomorrow

comes and tomorrow goes,  and the distance between us grows and grows.

       Around the corner! His house is only three miles away from here. One day a postman came.  "Here's a telegram (电报) for you, sir," he said.  I opened it and was surprised.  "Jim died today. " And that's what we get in the end.  Around the corner,  a friend is gone.

       So remember: If you love your friends and family, tell them and show your love to them.  When you

think that it is the right time, it might be too late.

1. Where did the writer's friend live?      

_______________________________________________________________________

2. Did they meet each other very often?      

_______________________________________________________________________

3. How far is the friend's house away? 

                                                                                                                                               

4. What happened to the writer's friend?      

________________________________________________________________________

5. What should you do if you love your friends and family?      

________________________________________________________________________

单项选择题