摁下彩电遥控器的待机开关，使彩电处于待机状态时，彩电仍在消耗电能．若每台彩电待机功率为9瓦，每天待机按20小时计算，一台彩电每天因待机消耗的电能为______度；这么多电能可供一盏25瓦台灯正常工作______小时．
①∵P=9W=0.009KW，t=20h，
∴一台彩电每天因待机消耗的电能为：W=Pt=0.009KW×20h=0.18KW•h=0.18度．
②∵P灯=25W=0.025KW，
∴灯正常工作的时间为：t灯=
=W P灯
=7.2h．0.18KW•h 0.025KW
故答案为：0.18；7.2．
| 完形填空。 | |||
| Life is not easy, so I’d like to say “When anything happens, believe in yourself.” When I was a young boy, I was 1 shy to talk to anyone. My classmates often 2 me. I was sad but could do nothing. Later, 3 _ happened, and it changed my life. It was an English speech contest(竞赛). My mother asked me to 4 it. What a terrible idea! It meant I had to speak 5 all the teachers and students of my class. "Come on, boy. Believe in yourself. You are sure to win.” Then mother and I talked about many different topics. At last we reached the topic “Believe in yourself.” I tried my best to remember all the speech and practiced it over 100 6 . With my mother’s great love, I did 7 in the contest. I could hardly believe my 8 when the news came that I had won the first place. I heard the cheers from the teachers and students. Those classmates who once looked down on me now all said "Congratulations!" to me. My mother hugged (拥抱)me and cried excitedly. 9 then, everything has changed for me. When I do anything, I try to tell 10 to be sure and I will find myself. This is true not only for a person but also for a country. | |||
| ( )1. A. so ( )2. A. made faces at ( )3. A. something ( )4. A. join ( )5. A. about ( )6. A. times ( )7. A. good ( )8. A. speech ( )9. A. Since ( )10. A. me | B. too B. looked after B. nothing B. take part in B. with B. words B. well B. result B. Except B. someone | C. very C. caught up with C. anything C. make C. before C. sentences C. bad C. ears C. From C. myself | D. quite D. laughed at D. everything D. get D. among D. topics D. badly D. hands D. Before D. everyone |