________ he had not hurt his leg, John would have won the race．

A．If

B．Since

C．Though

D．When

I had just stepped out of the bathroom and was busily drying myself with a towel ________ I heard the steps．

A．while

B．when

C．since

D．after

________ environmental damage is done, it takes many years for the ecosystem(生态系统)to recover．

A．Even if

B．If only

C．While

D．Once

This is a very interesting book．I’ll buy it, ________．

A．no matter how it may cost

B．how may it cost

C．how much may it cost

D．however much it may cost

Progress so far has been very good．________, we are sure that the project will be completed on time．

A．However

B．Otherwise

C．Therefore

D．Besides

We won’t keep winning games ________ we keep playing well．

A．because

B．unless

C．when

D．while

________ he was the last man I wanted to see, I did all I could to help him．

A．As

B．Now that

C．In case

D．Though

－May I go to play football with Dick now, Dad?

－No, you can’t go out ________ your work is being done．

A．before

B．until

C．as

D．after

________ you dislike ancient monuments, the temple is worth a visit．

A．As if

B．Ever since

C．Even if

D．Whenever

I’ll give you my telephone number ________ you might want to get in touch with me．

A．unless

B．so

C．in case

D．once