Special questions

They begin with a question-word (why, who, what, where, when, how, whose, which) or word-combinations: how + adjective / adverb; what + noun

Tense	Questions
Present Simple	Why do you like abstract art? does he Why are they busy? is he
Present Continuous	What are you doing now? is he
Present Perfect	How many letters have you sent yet? has he
Present Perfect Continuous	How long have they been studying English? has she
Past Simple	you Who did he see at the meeting yesterday? they etc.
Past Continuous	Whatwere you, they, doing when we arrived? was he, she, it, I
Past Perfect	he Where had she lived before he (she, they) moved to Paris? they etc.
Future Simple	you What will he do in summer? they etc.
Future Continuous	you Where will they be staying while in Paris? he etc.
Modal Verbs	Where can I leave my bags? When should they contact you?

Note! If a question has a preposition it is usually put at the end of the sentence.

E.g.: She was talking to an old friend.

Who was she talking to?

He is looking at his girl-friend.

Who is he looking at?