第五节 修饰原因的定语从句
当先行词是表示原因的名词reason时，其后的定语从句一般有why, for which引导，有时可以省略。如果关系词在句中做主语或宾语，可用that或which引导。
一、 reason why 从句
【释义】
reason后的定语从句一般有why引导，在从句中做原因状语，相当于for which。
【举例】
① This is the reason why I turned down your proposal.
这就是我驳回你的提议的原因。
② She never told me the reason why she didn’t accept my invitation to the ball that day.
她从未告诉过我她那天拒绝接受参加舞会的邀请的原因。
③ The reason why you failed in the exam was that you were too careless.
你考试失败的原因是你太粗心了。
【要点提示】
reason可表示“原因”，也可表“理由”，表示原因时后面可接why引导的定语从句，表示“理由”时常采用have (no/good) reason to do something的结构，而不用从句做定语，应注意区别。
二、 reason for which 从句
【释义】
该句型是上一句型的变体，for which与why相同，可以互换使用。
【举例】
① That is the reason for which I choose to live in the suburbs.
那就是我为什么选择在郊区居住的原因。
② Do you know the reason for which he has got such a promotion?
你知道他被提升的原因吗？
【要点提示】
for which中的介词也可置于句末，for置于句末时可使用关系词that, 也可省略不用，在英语中又有“句末介词可以省略”这一规律，这就是为什么reason后的定语从句可以没有关系词。注意下面句子的演变：
This is the very reason why I want to kill you.
This is the very reason for which I want to kill you.
This is the very reason which/that I want to kill you for.
This is the very reason ○I want to kill you for.
This is the very reason ○ I want to kill you
三、 reason that/which 从句
【释义】
reason后可接定语从句，也可接同位语从句。接定语从句时，如果关系词在从句中做主语或宾语则用that 或which，如果是同位语从句则只能用that。
【举例】
① I won't believe the reason (that/which) he told us for his late arrival.
我不会相信他所告诉我们的他晚到的原因。（定语从句）
② There is no reason (that) you can find for taking a holiday.
你找不到休假的任何理由。（定语从句）
【要点提示】
上面1，2句中关系词在从句中做宾语，3句中关系词在从句中做主语。英语中当先行词是reason时，关系词在从句中做主语和宾语的时候比较少，一般都是做状语，关系词还是以why 和for which较多。
四、 for the reason that 从句
【释义】
该句型不是定语从句的句型，reason后that从句是同位语从句，表示原因，而非结果。
【举例】
① He was killed in the car accident for the reason that he drove after drinking.
他因酒后开车而在车祸中丧生。
② He fell ill for the reason that he overworked.
他因工作劳累过度而病倒。
五、 The reason why … is that …
【释义】
该句型表示“之所以……是因为……”。
【举例】
① The reason why he got promoted was that he did excellent work.
他之所以被提升是因为他工作出色。
② The reason why our country is developing so fast is that we have been carrying out the opening up and reform policy.
我们国家之所以发展这么快，是因为我们实行了改革开放的政策。
【要点提示】
该句型可以有变化：
The reason for which … is …
The reason for … is ….
The reason for which he failed was that he was too careless.
The reason for his failure was his carelessness.
The reason for which he was promoted was that he did excellent work.
The reason for his promotion was his excellent work.
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