Warning: file_put_contents(): Only 0 of 5037 bytes written, possibly out of free disk space in /home/www/wwwroot/zidian/69228.com/index.php on line 55 免费黃色三級片在线观看20房东,黄页免费在线观看,国产一级无码精品AAAA免费
1. N the reciprocal of the arithmetic mean of the reciprocals of a set of specified numbers: the harmonic mean of 2, 3, and 4 is 3( + + )–1 = 3 調(diào)和平均值