It was on a cold winter evening_______ his father left home and was never back.
Doctors say that exercise is important for health, but it ________ be regular exercise.
One of our rules is that every student ________ wear school uniform while at school.
The new law states that people ________ drive after drinking alcohol.
—Good morning. I've got an appointment with Miss Smith in the Personnel Department.—Ah, good morning. You ________ be Mrs. Peters.
It ________be the postman at the door.It's only six o'clock.