Correct errors in text file.

[pawlo392]

I trying to write a program, which will correct errors in text file, for example TOm--> Tom, EUrope-->Europe, but if word has two letters, for example IT, program will ask the user if he wants to change second letter.I must use re.sub.
I don't have idea. I have:

import re
def correct(to_file):
    with open(to_file,'r') as f:
        for line in f:
            for word in line.spilit():

But, How to take into account the conditions of the task in re.sub..

[perfringo]

What have words with two letters in common? len(two_letter_word) == 2

[pawlo392]

I have now:

def correct(to_file):
    with open(to_file, 'r') as f:
        text = f.read()

    for word in text.split(" "):
        if len(word) == 2:
            print(word)
            x = int(input("DO you want to change second letter? (YES=1/NO=0):"))
            if x == 1:
                list2 = re.sub('([aA-zZ][A-Z]+ )','what here', text)

        else:
            list1 = re.sub('([A-Z][A-Z][a-z]+)',what here, text)



    print(list1)
    print(list2)

But, I don't have idea what to write here: "what here". I want to change only second letter.