One of the requirements for a fire is that the material _________ to its burning temperature.

Few people paid full attention to their healthconditions ________ they were seriously ill.

There is a new problem involved in the popularity of private cars _______ road conditions need _______.

Would you mind not littering in the classroom — ______ I’ll pick up the waste paper

There _______ an exercise book and three books on the teacher’s desk.