---Did you notice Tom was busy all day in his office?---Oh, yes, he has just finished his business tour of Chicago. He has a lot of work to ___.
. She insisted that she ______ somebody in the house.
——I must apologize for _______ ahead of time.——That's all right.
If you had not helped them, they ______ in London now.
A piece of ______ music will make you happy.
Greatly ______, the students made up their minds to work at English even harder.