look up 是动词和副词构成的短语，意思是查找，是及物动词短语，如果宾语是名词可以放在其后，也可以放在他们中间，但是如果宾语是代词，这个代词就只能放在他们之间了。例如，When you meet soe new words，you can look them up in the dictionary.
When you meet a new word during reading ，you can look the word in a dictionary.
look up 后面加名词，动名词或者代词的宾格。
代词必须放在中间名词可以放在中间，也可以放在后面look them uplook up these words
look up：
look up 译为“查找、拜访某人“等义，根据副词”up“为”向上“之义，look up 也可译为”向上看“
例：
(1). I always look up the words I don'know in the textbook.（用作”查找“之义时，后可直接跟宾语。）(2). We looked him up on saturday morning.
