问题 选择题
如图所示,理想变压器原、副线圈的匝数比为10:1,b是原线圈的中心接头,电压表V和电流表A均为理想电表.从某时刻开始在原线圈c、d两端加上交变电压,其瞬时值表达式为u=220sin100πt(V).下列说法正确的是(  )

A.当单刀双掷开关与a连接时,电压表的示数为22V

B.当单刀双掷开关与b连接时,电压表的示数为11V

C.当单刀双掷开关与a连接,滑动变阻器触头P向上移动的过程中,电压表的示数不变,电流表的示数变大

D.单刀掷开关由a扳向b时(滑动变阻器触头P不动),电压表和电流表的示数均变大

答案

答案:D

填空题

缺词填空。

     A Bag of Kindness "Boys and girls, tomorrow I want you to bring a cup of macaroni (通心粉) for our

craft class, OK?" These (1)w______  from my teacher rang in my mind all evening. I was afraid of the next

day

because I knew we had no macaroni at home. Living in an alcoholic (嗜酒的) family, we never had too

much of anything (2)e______ beer bottles.

     I went home after school. Where could I find macaroni? I knew that the local bottle shop gave ten cents

for a beer bottle, so I decided to sell some bottles to get money for macaroni.

     I started to (3)c______ the bottles. After selling those bottles, I earned eighty cents. Although I did my

(4)b______, I still had no macaroni for my craft class. "Weren't you (5)l______when I asked you to bring it,

John?" my teacher asked. I went red in the face. I didn't know what to say and other children started laughing.

Then a little girl, Rosalyn, who sat beside me turned to me and said,"You can have some of (6)m______."She

offered a bag of macaroni to me. The (7)k______ in her eyes made me cry and I ran out of the room.

     I (8)n ______ took her macaroni or thanked her for her bag of kindness. However, I often think about

Rosalyn and the way she turned to save me that day. I used to spend a great deal of my life complaining and

keep kind people like Rosalyn (9)a______. After that class, I (10)c______. I am grateful to all the people like

Rosalyn that made this world a better place to live in.

单项选择题 A1/A2型题