how long did you stay here how often do his parents let him watch TV?where do they come from

what when how who where ...开头的特殊疑问句,在提问的时候,
一般来说,一般现在时,一般过去时句子的行为动词要使用助动词do(does,did）
例：What subjects does he study in the university?
When did you go to school yesterday?
但是,在正在进行时,一般将来时,就不用 do(does,did）,因为要用助动词：be/shall/will
例：What are you reading now?
When will you go to see a film?
或者,是动词BE句子不用do(does,did）
例：Who is your English teacher?