It's very kind____you.

It 's very ( )of sb (to do sth)
意思是 你做~~真是太~~了。
比如It's very foolish of you to do that thing .你做那件事真是太愚蠢了。

of
你真是太好了！ 太棒了！
It's very glad/kind/pleasure of you！
意思都一样！

of 与人有关，可以表述人的通常用OF
只要能够翻成you are very (kind)就是用OF

填of。固定搭配常用语be kind of you

of , kind 是用来修饰you 的，可以说you're kind
要是物的话,则要用for

of，意思是你真是太好了。