题目

右图是小华设计的一种节能电梯工作原理图，R是一个力敏电阻，当电梯上无人时，力敏电阻受到的压力变小，阻值变大，电磁铁的磁性变   ▲   ，触点3与触点   ▲   （选填“1”或“2”）接触，电动机的转速变小，电梯变慢，从而达到节能目的. 答案：弱       1---- I’m sorry. That wasn’t of much help.    ---- Oh, ______. As a matter of fact, it was most helpful.    A. sure it was         B. it doesn’t matter      C. of course not       D. thanks anyway