如图5所示电路，电源两端电压保持不变，图中①、②、③是电流表或电压表。当开关S闭合后，两灯均发光，三个表均有示数。下列说法正确的是
A．①、②可能同是电压表
B．②、③可能同是电流表
C．①、③不可能同是一种表
D．②、③不可能同是一种表
答案：D
两灯均发光，既不能断路也不能短路，有两种方案如图：
A、①②都是电压表，电路是断路，两灯均不发光，故A错误；
B、②③都是电流表，电源被短路，两灯均不发光，故B错误；
C、根据两种可能方案分析①③只能是同一种表，故C错误；
D、根据两种可能方案分析②③不能是同一种表，故D正确．
故选D．
| :完形填空。 Dick goes to an evening party with his parents. He is very happy to see others singing and 1 in the party. But suddenly he can't find his 2 . He is very afraid. _3_ he begins to cry. When Mrs. Smith hears his cry, 4 comes over. "Can I 5 you, my little boy?" Mrs. Smith asks him kindly. But Dick doesn't 6 her. He still cries. Mrs. Smith asks again, "What's your name? Where do you live? Tell me your name and 7 ." The boy still doesn't say anything. At this time, Dick's mother runs to him, "My dear boy! I find you finally!" Mrs. Smith speaks to the mother, "Your son is very lovely. But I am 8 that he can't speak." " 9 !" Dick cries. "I can speak. But Mother says little 10 can't speak to strangers (陌生人)." | ||||
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