python - Search a list using a string -

i have list of lists:

 = [['andy', 'dear', 'boy', 'tobe', 'todo'],        ['where', 'what', 'when', 'how'],        ['korea', 'japan', 'china', 'usa'],        ['tweet', 'where', 'why', 'how']] 

i have three questions exact:

1. how retrieve sub-list list using particular element keyword?
   instance, want retrieve lists having element 'why' in them? is
   best possible way of doing so?
2. how retrieve sub-list list using part of particular element keyword?
   instance, want retrieve lists having elements containing 'wh' beginning
   characters of of elements?
3. how position or index of resulting sub-lists of these 2 searching methods?

i familiar concept of retrieving elements list matching particular keyword, confusing when comes retrieve lists matching particular keyword...

any guesses? in advance.

simple , straight

elem = 'why' index_li = [] idx, item in enumerate(a):     word in item:         if word.startswith(elem):             index_li.append(idx)             break print index_li 

example

>>> elem = 'wh' ... index_li = [] ... idx, item in enumerate(a): ...     word in item: ...         if word.startswith(elem): ...             print word, item ...             index_li.append(idx) ...             break ... print index_li ['where', 'what', 'when', 'how'] ['tweet', 'where', 'why', 'how'] [1, 3]