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until与unless的区别

2013-05-23 20:03阅读：

http://blog.sina.cn/dpool/blog/u/2428182620

世纪金榜高中全程学习方略选修7单元质量评估(三) Unit21
---May I go and play with Tom this afternoon, Mom?
---No, you can’t go out ____ your homework is finished.
A. before B. while C. until D. unless
答案是C，但是为什么不能选D。

解释：
until 表'直到', 强调时间的延续,引导时间状语从句。而unless表'除非', 强调条件,引导条件状语从句。上述题目中no 后用逗号，“you can’t go out” 承接否定词no，强调“你不能出去”的状态一直延续到“你作业被完成。”笔者认为：如果no 后用句号，可用unless，强调条件，意为：“如果你的作业未完成，你就不能出去。”例如：
1. I didn't know the news until my teacher told it to me.
动词 didn't know 表明该句强调时间的延续, 表'我不知道这消息'的状态一直延续到'老师告诉我', 因此应用until 引导时间状语从句。
2. I couldn't know the news unless my teacher told it to me.
动词couldn't know表明该句强调条件,表'我不可能知道这消息, 除非老师告诉我', 因此应用unless引导条件状语从句。
练习：
1. Owen wouldn't eat anything ______ he cooked it himself.
A. until　　　B. since　　　　C. unless　　　D. while
【答案】C 【来源】09四川
2. 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
【答案】C 【来源】08天津
3. _____ you call me to say you're not coming, I'll see you at the theatre.
A. Though B. Whether C. Until D. Unless
【答案】D 【来源】04全国2
4. ______ our manage objects to Tom's joining the club, we shall accept him as a member.
A. Until B. Unless C. If D. After
【答案】B 【来源】10上海
5. All the photographs in this book, _______ stated otherwise, date from the 1950s.
A. unless B. until C. once D. if
【答案】A 【来源】12陕西
6. A good storyteller must be able to hold his listeners' curiosity_____ he reaches the end of the story .
A．when B．unless C．after D．until
【答案】D 【来源】03上海春考
7. --- Was his father very strict with him when he was at school?
--- Yes. He had never praised him _____he became one of the top students in his grade.
A. after B. unless C. until D. when
【答案】C 【来源】03北京春考
8. Simon thought his computer was broken ____ his little brother pointed out that he had forgotten to turn it on.
A. until B. unless C. after D. because
【答案】A 【来源】05北京春考

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