21. Here's my card. Let's keep in ____.
A. touchB. relation
C. connectionD. friendship
【解析】选A keep in touch (with)是一种固定搭配。
22. ____ in the regulations that you should not tell other people the password 0f your e-mail account.(2005上海)
A. What is required B. What required
C. It is required D. It requires
【解析】选C用 require 被动式，It为形式主语。
23. ____ from other continents for millions of years, Australia has many plants and animals not found in any other country in the world. (2005湖北)
A. Being separated
B. Having separated
C. Haring been separated
D. To be separated
【解析】选Cseparate是及物动词，句意为“已经分开几百万年”，因此用分词完成时的被动语态。
24. Hospital staff burst into cheers after doctors completed a 20-hour operation to have ____ one-year-old twins at the head. (2004上海)
A. isolated B. separated
C. divided D. removed
【解析】选B separate用于“把两者分开”，isolate意为“隔离”。
25. The manager has fallen asleep where he ____,without undressing. (2005安徽)
A. was laying B. was lying
C. had laid D. had lied
【解析】选B语境是“经理躺着睡着了”。
26. Modern plastics can ____ very high and very
low temperatures．(2005山东)
A. standB. hold
C. carryD. support
【解析】选A句意为“承受高温或低温”，故选stand。
27. Now that she is out of job, Lucy ____ going back to school, but she hasn't decided yet. (2004 北京)
A. had considered B. has been considering
C. considered D. is going to consider
【解析】选B句意“一直在考虑重返工作岗位”，显然说话时还在考虑，所以用现在完成进行时。
28. When ____, the museum will be open to the
public next year.
A. completedB. completing
C. being completedD. to be completed
【解析】选A该题从句使用了省略形式，省略了与主句主语一致的主语 the museum 和系动词 is。在时间状语从句和条件状语从句中，若从句主语与主句主语一致，同时从句谓语动词又含有系动词be，常可省略从句主语与系动词be．
29. This is an illness that can result in total blindness
if ____.
A. leaving untreatedB. left untreated
C. leaving to untreatD. left untreating
【解析】选B if后的逻辑关系是：这种病被忽视未被治疗，表示被动关系，通过两个分词left和untreated表示。完整句子为：if it is left untreated，分词作非谓语动词可带连词。
30. The manager decided to give the job to ____ he
believe had a strong sense of duty.
A. whoeverB. whomever
C. whoD. no matter who
【解析】选Awhoever引导宾语从句，作介词to的宾语。但同时又做主句的主语，不能用whomever；而no matter who 引导让步状语从句，所以也不能用。