I was given three books on cooking,the first ( )I really enjoyed 答案是填of which

问题描述:

I was given three books on cooking,the first ( )I really enjoyed 答案是填of which
为什么不能填that,把first看作一个名词呢

这是一道简单的定语从句带介词的选择题,答案是B.意思是其中的第一本是我真的喜欢的.这样的定语从句中,前面还可以是the second ,the last ,half ,30% 等,尽管意思有所不同,但答案都是...of which.
单独first不能想当然看做名词,但the first 合在一起就相当于一个名词.由于其前面是逗号,所以必须是附属于前句的从句.如果是句号这个句子结构要调整,可以直接说:i really enjoyed the first .