5．The professor paused as if________his students to ask questions on the point he had just made.
A．expecting B．having expected
C．expected D．to have expected
解析：选A。当as if从句的主语和主句的主语一致，且从句又包含充当谓语的be时，从句的主语和be就常常省略。
4．On one side of the road trees will be planted，and________.
A．on the other are flowers and grass
B．on another flowers and grass
C．on the other flowers and grass
D．on another are flowers and grass
解析：选C。并列句中，如果后面分句和前面分句有相同的词，通常可以省略，以免重复。
3．Be careful with such things.If you________，you’ll drop them.
A．don’t B．aren’t
C．will D．do
解析：选B。if引导的条件状语从句中常用一般现在时表将来。If you aren’t后省略了careful with such things。
2．(2010年安徽芜湖一中一模)-What were you trying to prove to the police?
-________I was last night.
A．That B．When
C．Where D．What
解析：选C。此处是一个省略回答。完整的句子是I was trying to prove to the police where I was last night。即我极力想要向警方证明我昨天晚上在什么地方。其他选项语意不通顺。
本单元语法--省略
1．-How are you getting on with your work?
-Oh，I’m sorry.Things aren’t going so well as________.
A．plans B．planning
C．planned D．to plan
解析：选C。as planned＝as they were planned。
5．It is known to all that______you exercise regularly，you won’t keep good health.
A．unless B．whenever
C．although D．if
解析：选A。unless “除非”；whenever “无论何时”；although “尽管”；if “如果”。句意：众所周知的是，除非你进行有规律的锻炼，否则你不会保持身体健康。
4．________ you’ve tried it，you can’t imagine how pleasant it is.
A．Unless B．Because
C．Although D．When
解析：选A。此题考查状语从句的连接词。unless “除非，如果不”；because “因为”；although “虽然”；when “当……时候”。
3．We won’t keep winning games________we keep playing well.
A．because B．unless
C．when D．while
解析：选B。此题考查条件状语从句。句意：我们不会一直赢得比赛的胜利，除非我们一直打得好。根据句意分析，状语从句与主句是条件与结果的关系。
2．(2008年高考天津卷)We’ll have a picnic in the park this Sunday________it rains or it’s very cold.
A．since B．if
C．unless D．until
解析：选C。句意：除非下雨或天很冷，我们将在本周日去公园野餐。从句子之间的逻辑关系判断此处应为条件句，且为否定条件，相当于if...not，故排除if，而选unless。A项since表因果关系。D项until只能引导时间状语从句，故排除。
1．(2008年高考全国卷Ⅱ)A small car is big enough for a family of three________you need more space for baggage.
A．once B．because
C．if D．unless
解析：选D。句意：如果你不需要更多存放行李的空间，一辆小汽车对三口之家便足够了。once一旦……；because因为……；if如果……；unless如果不……。