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=220 sin100πt（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22 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：D
| 完形填空。 | |||
| Mr Black was once a policeman. He was a 1 person. He liked to have a walk in the park after breakfast. It was very cold 2 a winter morning. Mr Black was walking along the street when he heard a 3 for help. He turned around but could see nobody. He stopped and looked here and there. At the moment, a boy 4 to him. The boy was in such a hurry 5 he couldn’t say a word except 6 towards the river. Mr Black ran to the river as soon as possible. _7 of them ran along the river and saw a girl in the water. She was 8 a piece of wood. It was carrying her away. It was too 9 . Without a word, Mr Black took off his clothes as 10 as he could, and jumped into the river. He 11 to the girl and tool her back near the 12 and lifted the girl up, and then the boy helped 13 her out of the water. Then they 14 a car and took the girl to the _15 . At last the girl’s life was saved, and she thanked them very much. | |||
| ( )1. A. lazy ( )2. A. in ( )3. A. cry ( )4. A. ran up ( )5. A. so ( )6. A. running ( )7. A. All ( )8. A. holding ( )9. A. heavy ( )10. A. slowly ( )11. A. swam ( )12. A. bank ( )13. A. push ( )14. A. lent ( )15. A. house | B. kind B. on B. noise B. looked up B. and B. pointing B. Both B. lifting B. exciting B. carefully B. ran B. village B. pull B. bought B. school | C. deaf C. at C. laugh C. rushed out C. that C. driving C. Neither C. taking C. dangerous C. quickly C. rode C. park C. bring C. stopped C. hospital | |
V