只能粗略讲一下,想再弄清楚一点,建议查词典（牛津、朗文、柯林斯一类的）~
1 seek（for) sth:跟look for意思差不多,牛津上的解释就是：to look for[第六版],[I,Ipr esp passive 尤用於被动语态,Tn] (after/for sth) look (for sth); try to find or obtain (sth) 寻找; 找到或得到（某事物）[第四版]
2 look (for sb/sth)：to try to find sb/sth 尽力寻找,寻找的东西可抽象（如solution）,也可具体,见下：
I can't find my book-I've looked everywhere.◆ Where have you been?We've been looking for you.◆ Are you still looking for a job?◆ We're looking for someone with experience for this post.）
3 前面两个（seek for、look for）都是强调“寻找”这一过程,find强调结果——“找到”
4 search,意指“搜寻、搜索”,牛津第四版的解释为：搜查（某人）; 细查（某物或某处）以搜寻某人[某物]; 搜索,通常用search (for sb/ sth)的结构,同样不知能否“找到”,只是强点要“寻”