—I hear you run for half an hour every day. —Right, we have to. It is one of the ______ in our school.
My shoes are worn out.They need_______.
He hadn’t worked hard at his lessons._______, he failed in the exam.
— When did the meeting begin? —At four o’clock.It ______ for 15 minutes.
It is said that the gravity on Mars is only about __________ of the gravity on earth.
After a short time, the bad news had ______all over the city and everybody knew it.