He looks very tired . He ____ to bed too late last night .
________ me what you wanted to know, I should not have wasted my time talking so much with you.
Every time she was in trouble, she went to him for help, as he said he ________ do anything for her.
—Where did you get The Frog written by Mo Yan?—I picked it up from a bookshop online if you ________ know.
When I lived with my roommates in the university, we ________ often talk into the night.
________ your letter, I would have set off two days ago.