look up 一般指在字典里查找单词什么的,
look up the word in the dictionary.
look for 指寻找,更倾向于找的过程,动作,(顺便提一下)
find也是寻找,但更倾向于结果.
I looked (look的过去式)for my shoes ,but I couldn't find them .
look over 多指检查,考试检查之类的
Please look over your exam paper carefully.
look at 看,瞧.更倾向于看的动作,(顺便提一下),see也是看,但倾向于结果.
I look at the blackboard,but I can't see anything.
look up ( 在字典中)查 look up the word in the dictionary
look for 寻找 I am looking for my pen.
look over (医生)检查 The doctor looked over the boy carefully.
look at 看 Look at the boys. They are playing basketball.
够详细吗?还有例句,望采纳!