Translation of "Unfair" in Chinese

It is unfair.

这不公平。

That was really unfair.

那真不公平。

- You should've rejected such an unfair proposal.
- You should have rejected such an unfair proposal.

你本该拒绝一个那么不公平的提议。

It would be unfair if we treated him so badly.

- 我們這樣待他，好像不是太好。
- 这样对待他似乎不太公平。