介宾短语可以充当什么成分

1.The book on the desk is mine.(on the desk 就是介宾短语作定语)
2.On hearing the news,she couldn't help crying.(on hearing the news作状语)
3.They are at work.(at work作表语)
4.Please leave it on the desk when you finish reading the book.(on the desk作宾语补语)
介宾短语就是介词和宾语所构成的短语。介宾短语的主要作用是在句子中作状语。在英语中，这类的短语有很多，如：on the desk中,the desk是作介词on的宾语，合在一起构成了一个介词短语。再如，in the river,in front of the classroom等。