－I fell and hurt my leg just now．－________．

A．Be careful

B．It doesn't matter

C．I'm sorry to hear that

D．Nothing serious

This book ________ Helen's．Look!Her name is on it．

A．mustn't

B．may be

C．can't be

D．must be

－May I go swimming, Mum?

－Certainly．But you ________ be back by 7 o'clock．

A．Can

B．may

C．must

D．need

Bill's grandpa buys a large house with a beautiful garden．It ________ be very expansive．

A．must

B．can

C．mustn't

D．can't

－Would you like to go shopping with me tomorrow?

－I'd like to．But I'm afraid I ________ do my homework first．

A．have to

B．can't

C．mustn't

D．needn't

He studies hard．He sometimes studies ________ 12 p.m．．

A．at

B．until

C．on

You must keep your rooms ________．

A．cleans

B．clean

C．cleaning

You ________ play football in the street．

A．must not

B．should

C．may

This room is ________, but it doesn't have ________．

A．big enough; windows enough

B．enough big; enough windows

C．big enough; enough windows

It's a good habit ________ for a walk after dinner．

A．to go

B．go

C．going