Yes,it's difficult. It's tough. It's unfair.

是的，那很困难，艰辛，不公平。

哈佛公开课 - 幸福课课程节选

it's unfair for developed countries to force them to participate in anti-global warming activities.

发达国家强迫他们参与对抗全球气候变暖的活动是不公平的，

全球变暖与国力 - SpeakingMax英语口语达人