－I'd like to book a room for tonight．

－Sorry, sir, but we don't have any rooms ________ at the moment．

A．available

B．usable

C．suitable

D．comfortable

To ________ the child's quick recovery, five doctors took turns looking after him day and night．

A．ensure

B．undertake

C．promise

D．indicate

Will you drop in at my house this afternoon if ________?

A．it is convenient for you

B．you are convenient

C．it is convenient of you

D．you will be convenient

－I think I can't achieve my aims．

－In my opinion, you shouldn't ________ such a task．

A．attempt

B．have attempted

C．manage

D．have managed

From the ________ look on his face I knew he was serious．

A．determined

B．determine

C．determination

D．being determined

It is five years ________ we joined the army．

A．before

B．that

C．when

D．since

It won't be long ________ he comes back for his dictionary．

A．since

B．that

C．when

D．before

Please hurry away ________ the policeman comes here．

A．until

B．before

C．when

D．as

He made a mistake, but then he corrected the situation ________ it got worse．

A．until

B．when

C．before

D．as

Don't get off the bus ________ it has stopped．

A．since

B．before

C．until

D．when