def chunk_sent(text1:str, n_words_per_chunk:int, n_prev:int):
    """
    Chunks sentences into chunks having n_words_per_chunk
    using a window that considers the last n_prev words of the previous chunk
    
    >>> some_text = "w1 w2 w3 w5. w6 w7 w8"
    >>> chunk_sent(some_text, 3,1)
    ['w1 w2 w3', 'w3 w5. w6', 'w6 w7 w8']
    """
    alpha = n_words_per_chunk - n_prev
    l_total = []
    l_parcial = []
    if len(text1.split())//alpha >0:
        n = len(text1.split())//alpha
    else: 
        n = 1
    for w in range(n):
        if w == 0:
            l_parcial = text1.split()[:n_words_per_chunk]
            l_total.append(
                " ".join(l_parcial)
            )
        else:
            l_parcial = text1.split()[w*alpha:w*alpha + n_words_per_chunk]
            l_total.append(" ".join(l_parcial))
    return l_total