Why ____ you keep troubling your mother with such question while he is busy . 

I＿＿＿＿＿＿Professor Jones had taught me this question. 

You did not go to the party yesterday, or I ___ you.

Maybe if I _______ literature, but not science then, I would be able to give you more advice now.

“Is John coming by train？” “He should, but he _____ not. He likes driving his car.”