If you don’t know the word you can in the dictionary.A. look it after B. look it upC. lo

问题补充：

If you don’t know the word, you can in the dictionary.

A. look it after

B. look it up

C. look for it

D. look at it

答案：

A. look it after

(答案→)B. look it up

C. look for it

D. look at it

解析：根据文章内容in the dictionary.可知答案为B，为查找的意思，只有look up。故选B