def show_word(word, guesses):
    """(string, [string]) -> string

    Return the word to guess with guessed letters filled in and
    underscores for un-guessed letters.

    >>> show_word("", [])
    ''
    >>> show_word("bacon", [])
    '_ _ _ _ _'
    >>> show_word("bacon", ['f', 'c', 'g', 'e'])
    '_ _ c _ _'
    >>> show_word("bacon", ['c', 'a', 'b', 'o', 'n'])
    'b a c o n'
    """
    word_list = list(word)
    for i, element in enumerate(word_list):
        if element not in guesses:
            word_list[i] = '_'
    return " ".join(word_list)