6. C Sure, I'll be glad to help
7. A thank you for inviting me

8. C It's up to you
9. A good idea
10. C the shortest way
11. B keen
12. C have seen
13. A in
14. D find it difficult
15.C teaching
16. B unless
17. B although
18. D exciting
19. D the
20. D wasn't he
21. B sure
22. C Would you mind
23. D a three-hour
24. B fluently
25. B how long
26. C had
27. C what I thought
28. A washed
29. A Was the circus built at the same time as the theater?
30. A My brother advised me not to lend him any money.
31. C The book I bought last week which is very interesting.
32. My father usually went sailing when he was a child.
33. B They have worked in this company for 6 weeks.

Xin ctlhn