who,whose,which,what作主语时,一般接一个一定动词而不是疑问动词:
Who pays1 the bills2?
哪个付帐?(一定动词)
Whose/Which horse won3?
哪个的/哪匹马赢了?(一定动词)
What happened?/What went wrong?
发生了什么事?/出了什么问题?(一定动词,可能的回答如We missedthe train/had an accident4大家误了火车/出了事故。)
但who,whose等后跟be+名词或人称代词时,要用疑问动词:
Who are you?
你是哪个?
Whose is this?
这是哪个的?
What is that noise?
那噪音是什么问题?
who,whose等作动词或介词的宾语时,整句当然需要用疑问动词。