def merge_words(sequences):
    """Merge successive words into phrase, putting space between each word

    Arguments
    ---------
    sequences : list
        Each item contains a list, and this list contains a word sequence.
    Returns
    -------
    The list contains phrase sequences.
    """
    results = []
    for seq in sequences:
        words = " ".join(seq)
        results.append(words)
    return results