—________I complete so much my homework now?— No, you ________.You can do it after supper.

(2011·江西高考)It ________be the postman at the door.It's only six o'clock.

According to the school rules, if a student _________ happen to damage something by accident,he/she should report it to a teacher or the office immediately.

—Where did you get this book?—I picked it up from a second­hand bookshop if you ________ know.

The boy is old enough to ---------himself.