You should be ________ a diet; otherwise you will get fatter and fatter.
—How was that? —I was chatting on line _____ the power went out.
Our teacher always speaks slowly and clearly in class _____.
—Are you satisfied with the answer?—Not at all. It couldn't have been ______.
By the time Mr Wang returned home from Beijing, his son's wedding _______.
So _______ that everybody wants to take a photo with him.