井底的沙窝里只盛着一小窝子水，是前一个来挑水的人下到井底舀水之后，水又从地下渗出来的。
B-Location I-Location I-Location I-Location I-Location I-Location O O O O O O O B-Thing O O O O O O O B-Thing O B-Person O O B-Location I-Location O B-Thing B-Time I-Time O B-Thing O O B-Location I-Location O O O O O