He couldn't conceal his envy of me/envy at my success.
他遮掩不住对我的忌妒[对我的成就的忌妒].
You should not conceal yourself from your teacher.
你不应该躲避你的老师。
If words were invented to conceal thought, newspapers are a great improvement on a bad invention.
假使语言是为了隐藏思想而被发明的, 那么报纸就是对这不良发明的一大改进。