He found it increasingly difficult;  _____his eyesight was beginning to fail.

A. though          B. for              C. but             D. so

 I hope you’ve got you own car, _________if you haven’t we may have to hire one.

A. because         B. so that          C. ever since      D. when

 They got two free tickets to Canada, ____ they’d never have been able to afford to go.

A. as a result     B. otherwise        C. therefore       D. at last

 Wild animals ________ tigers and pandas are becoming rare.

A. as follows      B. for example      C. such as         D. for instance

 ________ both sides accept the agreement will a lasting peace be established in this region.

A. Unless          B. As long as       C. If only         D. Only if

 --Why didn’t you tell him about the result of the test?

  --He rushed out of the room ______ I could say a word.

A. before          B. until            C. when            D. after

 Let me say sorry to her? No way! I would die I apologize to her!

A. after           B. before           C. until           D. while

 ______ time, animals have developed many ways to stay away from their enemies.

A. Through         B. On               C. By              D. Over

 you’ve understood all these rules，you’ll have no further difficulty.

A. Unless          B. Although         C. Until           D. Once

 ____ we are developing new technology at such a high pace ,the true challenge is to find new ways of using it.

A. Although        B. After            C. As soon as      D. Now that