您必须使用for，简单的if不足以检查一组未知的列表:

You'll have to use a for, a simple if is not enough to check an unknown set of lists:

for key in mydict.keys():
    if item in mydict[key]:
        print key

没有显式for语句的方法可能是这样的:

An approach without an explicit for statement would be possible like this:

foundItems = (key for key, vals in mydict.items() if item in vals)

返回与item关联的所有键.但是在内部，仍然存在某种迭代.

which returns all keys which are associated with item. But internally, there's still some kind of iteration going on.