Ten years has passed ______ the CCTV event People Who moved China took place in 2002.

A. when   B. while   C. before    D. since 

Tigers wait________ it is dark，then go out to find their food．

     A．since    B．until    C．a(chǎn)s   D．because

The family had to stay at hotel, _____it was raining hard.

A because    B. although    C. until       D. unless

Some of the students are nearsighted ______they spend too much time watching TV or playing online games.

A. when B. though C. because D. unless

 They didn't go to bed_____ the work was finished.

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

 Mary, put on your coat, ______ you'll catch a cold.

A. and B. or   C .so   D. but

We should give the boy another chance ________ he has made some mistakes.

A. though B. when C. unless D. because

 Studying in groups is necessary______ you want to do well in school.

A. if    B. until   C. unless    D. though

Come on,  _______ you will be late for school.

A. and               B. but           C. or          D. so

Ben was busy taking a training class. ______we had to wait for him for half an hour.

　　　 A.so　　 B. if　　 C. or　　 D. but