Warning: file_put_contents(/home/www/wwwroot/zidian/69228.com/cache/467c6c45c005dd00a4ba2b3077e54c5b.txt): failed to open stream: No space left on device in /home/www/wwwroot/zidian/69228.com/index.php on line 55 狠狠人妻久久久久久综合蜜桃,在线观看一级毛片免费,911精品国产91久久久久
1. N the absolute value of the reciprocal of the curvature of a curve at a given point; the radius of a circle the curvature of which is equal to that of the given curve at that point 曲率半徑→see also centre of curvature