good idea!A. WhatB. What aC. HowD. How a

问题补充：

good idea!

A. What

B. What a

C. How

D. How a

答案：

A. What

(答案→)B. What a

C. How

D. How a

解析：这是一个感叹句,由于idea是单数可数名词,所以选what a.