一个英语句子的语法分析，求助！！ 来自马丁路德金的where do we go from here的一个句子：

Question

Why is it that people have to pay water bills in a world that is two-thirds water?
请问that is two-thirds water是做什么成分的呢？two-thirds在这里是形容词性质吗？如果去掉这个修饰，句子主干变成a world that is water了，这样对吗？

Answer 1

Why is it that people have to pay water bills in a world that is two-thirds water?
这句主语是it，系动词is，why作表语。
that从句that people have to pay water bills in a world that is two-thirds water是it的同位语从句。
that is two-thirds water是定语从句修饰world。
two-thirds可以看作数词，修饰water。追问

a world that is two-thirds water这样表达我不能理解，不应该是a world that is of two-thirds water吗

追答

英语的表达可能不会完全归纳对应到汉语的意思
你 这种表达意思更清晰，符合中国人习惯。
但原文的表达也能让人看懂，而且对比突出效果更强。

Answer 2

that is two-thirds water 作定语从句，修饰先行词 world；two-thirds
相当于形容词性质；去掉 two-thirds 语法上没错，但意思就不符合原意了，原文说的是地球约 2/3 面积都是水。追问

a world that is two-thirds water这样表达我不能理解，不应该是a world that is of two-thirds water吗？

追答

都一样的，原文还更简洁些，这个应该是欧美人日常使用中较常用的吧。就像一楼说的，对比还明显些。

追问

多谢啦！！疑问得解

追答

不客气。