— I think Mr. Zhang may be in his office.— No, he _____ be there. I saw him ____ there just now.

In China when the traffic light is red, you ________ cross the road.

It has been announced that students _______ remain in their seats until all the papers have been collected.

---Will you stay at home until your sister comes back? ---Sorry, I _______. I have a meeting and have to go in ten minutes.

－Must I finish my composition (作文) right now?－No, you _______.You can hand it in tomorrow.