19.The teacher understands that ________ Maths had always been easy for him, it is not easy for the students.

A.　　 since　　 B. unless　　　　 C. although　　　　 D. when

18.He will come to call on you the moment he ________ his painting.

A.　　 finished　 B. will finished　 C. has finished　　 D. had finished

17.It is at least ten years ________ these trees were planted.

A.　　 when　 B. before　　　 C. since　　 D. as soon as

16.I was about to leave my house ________ the telephone rang.

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

15. ________ I came into the office, the teacher were having a meeting.

A.　　 While　　　 B. When　　 C. Once　　　 D. Since

14.The boy didn’t stop talking ________ the second bell rang.

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

13.His brother has worked there ________ he left school.

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

12.The light went out while we ________ supper.

A. had　　　 B. had had　　　　 C. were having　　　　 D. would have

11.________ he failed , he went on doing the experiment.

A. Even　　　 B. Yet　　　　 C. Although　　 D. in spite of

10.Write clearly ________ your teacher can understand you correctly.

A. since　　　 B. for　　　　 C. because　　 D. so that