search for 寻找；搜查；竭力想；苦想
例句：
搜索, 搜寻
We searched in vain for the missing child.
我们到处寻找那孩子, 但没有找到.
They were searching for fossils.
他们在找化石.
After he felt better, he searched for work at the various mills.
他感到好些后, 就在各工厂找工作.
They searched all the drawers for the missing paper.
他们翻了所有的抽屉找寻那份遗失的文件.
I have searched my mind for a reason, but can't find one.
我绞尽脑汁寻找理由, 但是没找到.
look for 寻找,寻求；指望,期待
1.寻找(某人或某物)
Why are the police looking for you?
为什么警察在四处找你?
Some birds are looking for food.
有些鸟在寻找食物.
2.〈口〉找(麻烦); 找(苦头)吃
That foolish fellow is looking for trouble.
那个愚蠢的家伙在自找麻烦.
3.希望得到
It's too soon yet to look for results.
要想知道结果那还太早.
search for一般是很认真正式的寻找,比如说i look for you for a while可以在东张西望找了人一会后说,如果换成search for,那么就是类似你以寻找失踪者的那种态度去找的（稍微夸张点,不过大概就是这个区别）
look for还有指望,期待,盼望的意思,比如 你代表你们班级去比赛,你们班级的同学会说 “we all look for you” 就是 “我们都指望你拉” 比如 “we all look for the finals of world cup 2010" 就是“我们都期待着2010南非世界杯的决赛”