如图所示的电路中，电源电压恒定，闭合开关S后，电路正常工作，则电压表测______（选填“L”或“R”）两端电压，过了一会儿，两电表的示数突然都变为零，则该电路中出现的故障可能是______（已知故障只出现在L或R上）．
（1）电压表的与电阻R并联，则测量的是电阻R两端的电压；
（2）电源电压不变，灯泡L和电阻R串联，电流表测量电路中电流，电压表测量电阻R两端的电压；
所以，这时引起电压表示数为0的原因有：①电压表的正负接线柱与电源正负极之间有开路，②电阻R被短路，③电压表被短路；
引起电流表示数为0的原因：①电路中某处有开路，②电流表被短路；
由于故障只出现在L或R上，所以不是电表被短路，应是电路中出现开路现象，且开路位置在灯泡L上．
故答案为：R；灯L开路．
请阅读下面各小题，选择方框中所给的短语。每个短语限用一次（每小题1分）
-Don’t worry. They won’t ____ you. 小题2:I used to ____ of the dark. So I always had the light on when I was sleeping. 小题3:As a student, you must ____ what the teachers say in class. 小题4:-Did you dance at the party? -No. In fact, I can ___ dance ___. 小题5:____ the my friends, I finished the projects in time. 小题6:We had our school sports meeting last week. Most of us ____ it. 小题7:What a beautiful skirt she is wearing! She always ___ much time __ buying clothes. 小题8:-Could you speak to Bob Smith? -Sorry, he ____ works here. 小题9:Don’t be angy，Mary. If you love him, you should believe in ____. 小题10:-How did you ___ the problems writing English? -I’ve got a pen pal in England. |