30. Learning how to repair motors takes a long time, _____________? 　　　　　

29. You must have been to the Great Wall, ____________? 　　　　　　　　　

28. Birds rarely build nests in our garden,_____________? 　　　　　　　　　

27. No one left here yesterday,_____________?　　　　　　　　　　　　　 　

26. Harry wouldn’t become a teacher if it hadn’t been for the holiday, __________? 　

25. It’s my son’s wedding next week, and I have to do my best for that,__________?

24. His wife had the carpets and the curtains cleaned, ____________? 　　　　

23. I don’t think that the necklace is made of diamond, __________? 　　　　　

22、---Let’s go and play football,__________? 　　　　　　　　　　　　　

---That’s wonderful.

21、----_____________will the foreign students be back from NanJing?

----In two days, I think .