23.　 That’s ______ they didn’t pass the exam.

22.　 We haven’t decided _____ and ______ we shall meet next time.

21.　 I don’t know _______ she can speak Russian or not.

20.　 It’s a fine day, ____ we have a wonderful time.

19.　 Li Ming was a brave boy, ______ he had one shortcoming.

18.　 Hurry up, ______ you’ll miss the next bus.

17.　 You may ______do it yourself ________ leave it to me.

16.　 I really don’t know ______ it is going to rain or not this afternoon.

15.　 _____ my father ______ my mother is a doctor. They are teachers.

14.　 _____you have a few more days’ rest,　 you’ll feel better.