解析：reason 的定语从句可以由 why 或 for which 引导；该定语从句中又有 when 引导的时间状语从句；
逗号后面的分句主语 all we can do 又出现一个定语从句，只是省略了关系代 词 that。
03 课后巩固1) Is this park ________ we visited last week?
A. which B. where C. the one
2) Do you remember the park ________ we visited last week?
A. where B. that C. the one
3) This is the park ________ I lost my phone last week.
A. where B. that C. the one
4) His illness will not develop to the point ________ no medicine can cure her.
A. where B. that C. as
5) A computer can only do ________ you have instructed it to do.
A. how B. that C. what
6) No one knows ________ in a million years.
A. what man will look like
B. what will man look like
C. man will look like what
7) I don’t know ________ or not.
A. whether he is at home
B. if he is at home
C. that he is at home
8) If you don’t understand something, you may research, study, and talk to other people ________ you figure it out.
A. because B. until C. when
9) ________ the average age of the population increases, there are more old people to care for.
A. As B. While C. As soon as
10) ________ you may have, you should face the challenge.
A. However a serious problem
B. However serious a problem
C. What a serious problem
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「虫虫讲英语」老少咸宜的英语学习号。有时候，语法换一种方式讲，就听懂了。
04 总结定语从句：作定语/ adj. 修饰先行词；
宾语从句：作宾语，放在动词或介词后；
状语从句：作状语，给主句增加信息量。
如果可以，抽15分钟时间，把前面几节课再看一遍：
定语从句、宾语从句和状语从句，都有自己的关系词或连接词：
对比之下，我们发现这点上比较容易混淆的是定语从句和宾语从句：宾语从句不仅有可以引导一般疑问句的 whether, if，还有引导特殊疑问句的 what 和 how。而定语从句是没有 what 和 how 等引导词的。
