A brilliant idea occurred to him, ______ to his research in the lab.
I _____ my son _____ a doctor, but he wasn’t good enough at science.
---- Tom, did Mr. Li join you in your discussion? ---- No, he _____, but he happened to have fallen ill.
Good heavens! There you are! We _____ anxious about you, and we _____ you back throughout the night.
---- You haven’t got the textbook for my chemistry course yet. ---- I know, and we _____ to get it for the last 5 weeks.
---- Hey. Look where you are going! ---- Oh, I’m terribly sorry ____.