20. 　　　　　each other for long , the two brothers decided to meet soon.

A. Not having seen　 　　　　 B. Not seen 　　　　　　 　　　　 C. Have not seen　　 　　　　 D. Not seeing

19. Tell John not to leave the house unless he 　　　　　that the lights ______ .

A. will make sure, turn off　　　　　　　　　　　　　　　　　　 　　　　 B. makes sure; are turned off

C. will make sure; will turn off　　　　　　　　　　 　　　　 D. makes sure; will be turned off

18. It was the training 　　　　　he had at school 　　　　　made him good jumper.

A. what; what 　　　　　 　　　　 B. what; that　　　 　　 C. that; that　　　　　　　 　　　　 D. that; which

17. It is difficult for any of us to eat better, exercise more, and sleep enough,________ we know we

should.

A. because　　　　 　　　　　　　　　 B. even if　　　　　　　　　 　　　　 C. unless　　　　　　　　　　 　　　　 D. before