题目

如图所示电路, 是一种声光报警电路的示意图，当电键S1和S2同时闭合时，会出现的现象是 () A、灯亮，铃响     B、灯亮，铃不响 C、灯不亮，铃响              D、灯不亮，铃不响 答案：B  Mrs.Smith often tells her son ________ too much meat.A. don't eat B. not eat C. to not eat D. not to eat