1）单独使用时，后不跟介词。如：
I looked but saw nothing. 我看了，但什么也没看见。
Look! Here comes the bus. 瞧！汽车来了。
Look before you leap. 三思而后行。
2）和at连用。如：
The teacher is looking seriously at us. 老师正严肃地看着我们。
Look at these pictures. How beautiful they are! 看这些画，它们是多么漂亮啊！
3）和其它某些介词或副词连用:
a、look after 照看，照料。如：
He is old enough to look after himself. 他年龄足够大，能照看自己。
b、look for 寻找。如：
I looked for you just now, but I didn’t find you. 刚才我到处找你,但没有找到。
c、look around 四下环顾，到处寻找。如：
He looked around but he saw nobody. 他四下环顾，但什么人也没看到。
d、look back on回想，回顾。如：
They often look back on the days they spent together. 他们常回顾他们在一起度过的日子。
e、look down on看不起。如：
Don’t look down on others.不要看不起别人。
f、look forward to 盼望。如：
We are looking forward to seeing you again. 我们盼望再见到你。
g、look into朝……里面看。如：
He looked into the box, but he saw nothing. 他朝箱子里面看了看，但没看到什么。
h、look on...as把某人看作。如：
We look on him as our friends.我们把他看作我们的朋友。
i、look out当心。如：
Look out! Don’t hit the tree. 当心！不要撞了树。
j、look over仔细检查；翻阅。如：
The doctor is looking him over. 医生正在给他做仔细检查。
k、look through浏览；仔细检查；看穿。如：
I have looked it through. 我已把它仔细地看了一遍。
l、look up抬头看；查；找出。如：
He looked up and smiled at me. 他抬起头，对我笑了笑。
If there are words you don’t understand, look them up in the dictionary. 如果你有不认识的单词可以查词典。
二、用作连系动词，意为“看起来”。
1）后跟形容词。如：
You look well/fine/healthy. 你看起来很健康。
The teacher looks happy. 老师看上去很高兴。
She looks pale. 她面色苍白。
2）后跟过去分词。如：
You look tired; you’d better have a rest. 你看上去很累，你最好休息一下。
3）后跟名词。如：
He looks a nice, honest man. 他看上去是个诚实的好人。