by which 和 by which time 引导定语从句用法一样吗？

IsaacZ

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In the office I never seem to have time until after 5: 30 p.m., _____c_____ many people have gone home.
A. that   B. which   C. whose time   D. by which time

答案是D. by which time 相当于 and by that time。但是by which不是已经相当于when了吗？再加一个time不是重复了吗


答：
拿 during which 和 during which time 为例：

给你几个例句看下（来源google)
1. I don't have to worry about the old age during which I even can't take care of ...
2. The average length of labor during which these women received their meperidine was under 12 hours.
3. US Congress: HR 1347, To extend the period during which members of the Armed Forces deployed in contingency operations may request and ...
4. Socially Awkward Situations During Which It Would Be Acceptable to Mess With Texas.
5. Fish evolve a longer lifespan by evolving a longer period during which they reproduce.

1. In this post, he share his experiences during the past 5 years at learndirect, during which time they have strategically adopted a range of open source ...
2. Entered the service a fourth time some time in the year 1781, as a volunteer under Colonel William Moore and served about one month during which time he was ...
3. They lay there for three weeks during which time they made friends with the ...
4. Have been fostering for five years, during which time they have fostered 20 children.
5. ... registry will occur on 9/24/2006 from 9 PM to 9:45 PM EDT, during which time you will be unable to register, renew or manage .

这些都是google上搜到的原版英文句子，可以看出一个规律：

during which的 中心语（先行词）大部分是表示时间段的名词例如 period 等；
而 duiring which time 的中心语（先行词）常常是具体的时间如 5 years 等。


相关参考：介词+which+time 引导定语从句，which做定语（during which time等）



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