Question

请帮忙分析一下这句话的句子成分

The water table is the underground boundary below which all the cracks and pores are filled with water.

这里的which和后面的一句话是which引导的名词性从句吗？
water table到底在cracks and pores的上面还是下面？

Answer 1

这是主系表结构包含了定语从句。
the water table是主语， is是谓语，the underground boundary是表语。
below which这里which指的是 boundary，所以是定语从句。
all the cracks and pores are filled with water是完整主谓宾结构，所以below which一起在句中做状语。

追问

我好像把这里的which后面的句子当成了同位语从句所以理解错了，请问这句话是怎么区分他是个定语从句而不是个同位语从句的呢？

Answer 2

答案是：water table在cracks and pores的上面。below which意思是在它下面，这里的它是代指the water table地下水位(线).。全句是由两个分句构成的并列句而非复合句。拆开看是：The water table is the underground boundary. Below the water table all the cracks and pores are filled with water.
不知我说明白没有。祝进步!

Answer 3

定语从句，water table和cracks and pores没有关系