look up和looking up的用法

look up 是动词加副词的结构，可以作谓语，意思是:向上看，抬头看；查阅，查找。常见短语是look sb up，look sth up.

looking up是由现在分加副词的结构，可与be的不同形式构成进行时，也可以作状语、定语、补足语等。

例如：

She looked up and saw me. 她抬头看见了我。

You can look up in the web page of his school for the phone number of Zhang Dong.有关张东电话号码，你可以查阅他所在学校的网页。

You can look up the meaning of the word in the dictionary.你可以在词典里查阅这个单词的意义。

I saw him looking up words in the dictionary.我看见但在词典里查生词。

前者为其原形！后者指正在进行时态