– Who didn’t turn off the light after school yesterday?– It ______ be Lucy. She told me she was the last one to leave the classroom.

—I think the man over there must be Bob. -- It_______ be him. He has______ to Australia. 

Being examined twice a year, whether it is a car or a bus or a truck, it is the rule that every driver____ obey in this city.

—Why，I didn’t get you on the phone.—We ________football on the playground when you phoned.

It’s said that there are plenty of hotels in that town. There _____ be any difficulty for you to find one to stay in.