18.2 關系副詞引導的定語從句
?
　 關系副詞可代替的先行詞是時間、地點或理由的名詞，在從句中作狀語。
1）when, where, why
　 關系副詞when, where, why的含義相當于"介詞+ which"結構，因此常常和"介詞+ which"結構交替使用，例如：
　 There are occasions when (on which) one must yield.　任何人都有不得不屈服的時候。
　 Beijing is the place where (in which) I was born.　北京是我的出生地。
　 Is this the reason why (for which) he refused our offer?　這就是他拒絕我們幫助他的理由嗎？

2）that代替關系副詞
　 that可以用于表示時間、地點、方式、理由的名詞后取代when, where, why和"介詞+ which"引導的定語從句，在口語中that常被省略，例如：
　 His father died the year (that / when / in which) he was born.　他父親在他出生那年逝世了。
　 He is unlikely to find the place (that / where / in which) he lived forty years ago. 他不大可能找到他四十年前居住過的地方。