look into 调查
A working party has been set up to look into the problem.
已成立工作组调查该问题。

look up 查阅
You can look up this word in the vocabulary.
你可以在词汇表里查这个词。

look down 看不起, 蔑视
I wish you wouldn't look down on this kind of work.
我希望你不要看不起这种工作。