题目

听一段对话，回答以下小题。【1】What’s Sam’s problem?A. He wants to have some dogs. B. He can’t sleep well. C. He doesn’t like his neighbors.【2】What causes Sam’s problem?A. His neighbors always fight at night.B. His parents always argue with each other.C. His neighbor’s dogs are noisy at night.【3】What will Sam possibly do with the problem?A. He will call the police.B. He will talk with his neighbors.C. He will close his windows at night.如图所示的电路中，要使灯L1、L2并联发光，则应闭合开关 [     ]A．S1 B．S1、S3 C．S2、S3 D．S1、S2、S3