特殊疑问句提问主语不要助动词?

特殊疑问句的疑问词如果充当主语,就不要再加助动词,如：
who is crying in the classroom?
who closed the door yesterday?
what is in the box?
只有在特殊疑问句中谓语动词是行为动词,并且不是对主语提问时,才要加助动词,否则都不要另加助动词.
如：He can swim.What can he do?
He is going to Beijing tomorrow.Where is he going?