问题
选择题
某交流电电源电压的瞬时值表达式为u=6 sinl00πt（V），则下列说法中正确的是（ ）A．用交流电压表测该电源电压时，示数是6V B．用交流电压表测该电源电压时，示数是6 C．用此电源给电磁打点计时器供电时，打点的时间间隔为0.01s D．把标有“6V 3W”的小灯泡接在该电源上时，小灯泡将被烧毁 |
V
答案
答案：A
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| 某交流电电源电压的瞬时值表达式为u=6sinl00πt（V），则下列说法中正确的是（ ） A．用交流电压表测该电源电压时，示数是6V B．用交流电压表测该电源电压时，示数是6 C．用此电源给电磁打点计时器供电时，打点的时间间隔为0.01s D．把标有“6V 3W”的小灯泡接在该电源上时，小灯泡将被烧毁 |
答案：A
阅读下面短文，根据短文大意和语境选择方框内的单词，并用其正确的形式填入空白处，使补全后的短文意思通顺，语法正确，结构完整。
I’m a student of Grade 9. I want to tell you something. In our school, many students have mobile phones. They think it’s 1 to have a mobile phone. Yes, the phones let students talk with their parents and friends at any time. But I don’t think it’s good for students to use them at school. Many students spend lots of time in 2 messages by mobile phone, some students even use them to play games in class or cheat (作弊) in the exams. Some students always hope to buy the new or 3 mobile phones and this will 4 their parents’ money. And my father tells me that most mobile phones can cause (引起) many health 5 . Could you do something to stop it? Yours, Sophia |