16. I returned home with some roses and only then __________ find my favorite vase missing.
| A．I did | B．did I | C．do I | D．I do |
31. A large sum of money has been raised for the ________ of the poorly-educated children in the mountainous districts.
| A．profit | B．favor | C．advantage | D．Benefit |
30.Little _________ that we were watching his every move, so he seemed to be going his own way in this business.
| A．he realized | B．he didn’t realize | C．did he realize | D．didn’t he realize |
29. The nutrients in ____ falls into the ocean will quickly become available to other living creatures.
| A．whichever | B．that | C．whatever | D．Wherever |
28. I don’t think you’ve quite__the seriousness of the situation. You seem to know nothing about it.
| A．recognized | B．mastered | C．grasped | D．Seized |
20．The river, ________ banks are covered with trees, is beautiful and it attracts many water birds.
| A．whose | B．what | C．of which | D．which of |