def complete_english(string):
    """
    >>> complete_english('dont do this')
    "don't do this"
    >>> complete_english('doesnt is matched as well')
    "doesn't is matched as well"
    """
    for x, y in [('dont', "don't"), ('doesnt', "doesn't"), ('wont', "won't"
        ), ('wasnt', "wasn't")]:
        string = string.replace(x, y)
    return string
