No black person was to ride a bus on Monday, December5, the day that Mrs. Parks came to trial.
請問，定語從句的先行詞是day ,為什么用 that引導？ 一般不是用what 嗎？
☆答：the day 在此與 Monday,December5同位，that 引導的是限制性定語從句。限制性定語從句以that 引導是常見的現象。句子里的日期已是特定的，其后的定語從句自然是限制性的了。例如:
Can you mention any one that we know?
Everything that could be done was done.
在表示時間的情況下，如果用 that可以代替at which， in which, on which則往往用that. 例如：
This is the time that the unjust man doth thrive.(莎士比亞)
By the time (that) you are ready, everybody will be gone.
The moment (that) the teacher entered ,everybody stopped their chatter.