于[yú] 基本解释：
新英汉大词典：
- 于(於)[yú]
- 介词- （表示时间、处所、范围等）:
famous all over the world; of world renown;闻名于世界
The Changjiang River rises in Qinghai Province.长江发源于青海。
- （表示动作的方向）:call to one's aid; ask people for help;求助于人
ask the way from a blind person; seek advice from one who can offer none问道于盲
- (用在动词后面，表示交与，付出等）:shift the misfortune onto sb. else; put the blame on sb. else;嫁祸于人
As a result of collective effort, the difficult situation changed into a favourable one.经过大家的努力，困难的局面终于让位于顺利的局面。
- （引进对象或事物的关系者）:not rest content with one's achievements; not rest on one's laurels;不满足于已经取得的成绩
dedicate oneself to education;献身于教育事业
- （表示起点或出发点）:out of ignorance;出于无知
of one's own free will; of one's own accord;出于自愿
- （表示比较）:This year's yield of wheat is higher than ever before.今年小麦产量高于往年。
Though death befalls all men alike, it may be weightier than Mount Tai or lighter than a feather.人固有一死，或重于泰山，或轻于鸿毛。
- （表示被动）:be laughed at;见笑于人
be recognized by society见知于世
- 名词- （姓氏） a surname:
Yu Qian于谦
例句与用法：
After much delay, he finished his paper at last.
Finally, they arrived at an agreement.
Only in 1687 did he at last publish his new theory.
Success lies not so much as in luck as in hard work.
I enrolled at the University of Vienna.
Our corporation was formed in 1994.