定语从句的关系副词有when、where、why。
1.when在从句中用作时间状语,其先行词须是表时间的名词;
列如 We will put off the picnic until next week, when the weather may be better.
2.where在从句中用作地点状语,其先行词须是表地点的名词;
列如 They went to the Royal Theatre, where they saw Ibsen's "The Doll’s house".
3.why在从句中用作原因状语,其先行词只有reason,并且只能用在限制性定语从句中。
列如 They went to the Royal Theatre, where they saw Ibsen's "The Doll’s house".