— They are quiet, aren’t they? — Yes. They are accustomed ______ at meals.
Provided that they are fit, I see no reason why they _____ go on playing basketball for another four or five years.
I have been staying up until midnight since Monday, _____ on my paper. I need to catch up on some sleep this weekend.
The place he suggested ______ hold the meeting is a five-star hotel.
It is said that he is focusing on another book on space exploration. When will it _____?
— What on earth are the police busy with?— They _____into how the plane crash came about.