Did we have the right dresses in which to appear before Lady Genmire? Wefelt very excited and unsure.
谢谢各位老师对大家之前问题解答，像请教一下，上面的句子Which 是指代前面的名词dresses,还是单独作为一个名词，表示什么的意思来用！
谢谢各位老师的帮忙！
in which to appear before Lady Genmire
which是关系代词，指代right dresses。这是介词+关系代词+to do不定式结构。这种结构用于正式语体，本质上是定语从句的一种简化形式，即定语从句省略了主语和be。主语一般在前面出现，be+to do 为be to do结构表示以后时间。所以这个句子与下面定语从句作定语的句子意义是相同的。
Did we have the right dresses in which we are to appearbefore Lady Genmire?
也可以用情态动词结构替换be to do结构：
Did we have the right dresses in which we should/could appearbefore Lady Genmire?
