(三)定語從句

　　1. The prevention and treatment of AIDS is (07.6)

　　The field in which we can cooperate

　　2. Medical researches are painfully aware that there are many problems_________ (08.12)

　　to which they still have no answers

　　強化練習

　　1. which is on the increase.

　　考點：本題考查非限制性定于從句 which 指代前句話的用法，考生不易想到。

　　2. as many famous stars who should have appeared did not come.

　　考點：在英語中表示過去應該做而實際上沒有做的事，要用should + have +過去分詞的句式。