鞭长莫及
beyond one'sgrasp

关公门前耍大刀
There's no need to teach a fish to swim.

严以责己宽以待人
to be severe with oneself and lenient with others

铁石心肠
a heart of steel

听天由命
to be guided by destiny

骄者必败
Pride goes before a fall. 

小Car笔记：

lenient：宽大的, 仁慈的  【例句】①Lenient parents; lenient rules.仁慈的父母; 宽松的规章制度  ②In your case, we are prepared to be lenient.根据你的情况，我们拟予从宽处理

中国成语英译系列>>