When we are young questions of we want to be when we grow up are common.A. whichB. whoC.

问题补充：

When we are young, questions of we want to be when we grow up are common.

A. which

B. who

C. what

D. how

答案：

A. which

B. who

(答案→)C. what

D. how

解析：考查名词性从句。句中what引导宾语从句，在从句中作表语，选C。