I wrote a letter of plaint, and the airline has promised to the matter.
A. look up
B. look into
C. look through
D. look for
网友回答
A. look up
(答案→)B. look into
C. look through
D. look for
解析：考查动词短语辨析。Look up查找；look into调查；look through浏览；look for寻找；句意：我写了一封投诉信，航空公司允诺调查此事。