题目

为了安全，汽车行驶时驾驶员必须系好安全带．当系好安全带时，相当于闭合开关，指示灯不亮；未系好安全带时，相当于断开开关，指示灯发光．符合上述要求的电路图是       A                  B                C               D   答案：C   —Can you see ________________?—No. Let’s go and have a look. Maybe we can help them.A. what was happening there 　　　 B. what are they doing thereC. what are they talking there 　　 D. what is happening there