五种介词短语
英语介词不可单独使用，只能与不同的此类构成介词短语来在句子中担当一个成分。
常用的五种介词短语
1.介词+名词：at the door, into the bag
2.介词+代词: for me, of others
3.介词+动名词: in doing so, to my saying that
4.介词+连接副词/连接代词/what从句:over what he had better do
5.介词+连接副词/连接代词+不定式：on how to do this
其他类型的介词短语
6.介词+介词短语：from across the street, until after dinner
7.介词+副词：from below
8.介词+复合结构：with the light on
9.介词+不定式(but/except)：did nothing but sleep介词 -- 连接词与词纽带
英语经常用介词来表示词与词之间的关系