important tool(工具)the computer is! -I think so.A. What aB. HowC. What anD. How an

问题补充：

important tool(工具)the computer is! -I think so.

A. What a

B. How

C. What an

D. How an

答案：

A. What a

B. How

(答案→)C. What an

D. How an

解析：因为后面名词tool为可数名词单数.故用what a/an又根据important的第一个音标为元音.故选C