------Mum，can I go out to play with Tom for just a while ？
------ _______ and do what you like.
| A．No way | B．Go ahead | C．It depends | D．Don’t worry |
.
—When will you be back, Peter?
—___________ a couple of days.
| A．On | B．In | C．For | D．By |
.
. All books ___________ to the library more than three days late will be subject to a fine.
| A．return | B．returning | C．to return | D．returned |
.
When he was only thirty years old, he had already experienced ___________ most people only experience when they are much older.
| A．what | B．which | C．who | D．when |
.
___________ in the sports world, a sportsman needs to train constantly to keep himself in best condition.
| A．Survive | B．Surviving | C．To survive | D．Survived |
.
Listen, Mike. She ________________ have done it. She's been with me at the shop all day.
| A．couldn't | B．shouldn't | C．needn't | D．wouldn't |