1. The reason why he could not go there was that his grades were too low. 他没能上电影学院是因为他的分数太低了。
1. 句中that引导的表语从句说明主语reason的具体内容，往往被看作是固定句型：The reason is / was that clause. 当主语是reason / cause时，一般不能用because或why引导表语从句，以免造成语意重复。当主语是This / That时，可以由because / why引导表语从句。例如：One reason is that people traveled to America from all European countries.
-- I drove to Zhuhai for the air show last week.
-- Is that ____ you had a few days off?
A. why B. when C. what D. where
2. why在句中是关系副词，引导定语从句，修饰先行词reason，同时它在定语从句中作状语，此时why = for which，但要注意：关系词在定语从句中作主语或宾语时，要用关系代词that或which。
【考例】(2002上海春招)Is this the reason ____ at the meeting for his carelessness in his work?
A. he explained B. what he explained
C. how he explained D. why he explained
[答案与解析]A what，how不能引导定语从句，排除B、C两项;the reason在定语从句中作explained的宾语，可填that / which，或者也可以省略。
2. Many people who saw the film were afraid to swim in the sea when they remembered the scenes in which people were eaten by the shark. 好多看过这个片子的人一想起片中鲨鱼食人的场面.就不敢下海游泳了。