四大皆空
All is vanity.
四海之内皆兄弟
All are brothers within the four seas.
四面八方
These folks come from in all directions (far and wide; there and everywere; length and breadth)
四海为家
I don't know where Jack is now; in my mind, he is a person who is here today and gone tomorrow.
未雨绸缪
take precautions before it is too late
目不识丁
not know A from B / an illiterate
失败为成功之母
Failure is the mother of success.
失之毫厘，差之千里
A miss is as good as a mile.
只要功夫深，铁杵磨成针
Little strokes fell great oaks.
毛遂自荐
to recommend one's own person
小Car笔记：
vanity：虚无，浮云
illiterate：文盲，目不识丁 【常用词组】①functional illiterate：职业上的文盲 ②illiterate population 未受教育的人口
recommend：推荐 【常用词组】recommend substitutes：推荐代用器