---Do you know who invented ________ telephone?

---No. But it is really________ most important invention.

A．/; the

B．the ;/

C．/ ;a

D．the ;a

消毒柜的加温温控器开路可引起（）故障。

A.按下电源开关，所有指示灯不亮

B.保温灯亮，不消毒

C.消毒灯亮，不保温

D.消毒灯亮，但没有消毒效果