---Do you know who invented telephone?---No. But it is really most important invention.A.

问题补充：

---Do you know who invented telephone?

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

A. /; the

B. the ;/

C. / ;a

D. the ;a

答案：

A. /; the

B. the ;/

C. / ;a

(答案→)D. the ;a

解析：考查冠词。the telephone在特定和专有事物或名称前要加定冠词。a most非常。句意：——你知道是谁发明了电话吗？——不知道，但它真的是一个非常重要的发明。