ass日本风韵熟妇pics男人扒开女人屁屁桶到爽|扒开胸露出奶头亲吻视频|邻居少妇的诱惑|人人妻在线播放|日日摸夜夜摸狠狠摸婷婷|制服 丝袜 人妻|激情熟妇中文字幕|看黄色欧美特一级|日本av人妻系列|高潮对白av,丰满岳妇乱熟妇之荡,日本丰满熟妇乱又伦,日韩欧美一区二区三区在线

44%和71%,。Taking earthworm (Eisenia foetida) as the study object, six surface specimens including motionless, extending and shrinking of the forehead and body were prepared according as its movement characteristic. The soil adhesion force and sliding resistance experiments of earthworm nonsmooth surface specimens and steel specimen were conducted on via a tiny adhesion testing system. The results showed that the shrinking specimen had best reducing soil adhesion force and sliding resistance ability, then were motionless specimen and the extending specimen respectively. The forehead sample had better reducing soil adhesion force and sliding resistance ability than the body sample. In the test condition, the soil adhesion force and sliding resistance of the forehead sample were 25% and 61% of that of the steel specimen respectively. The soil adhesion force and sliding resistance of the body sample were 44% and 71% of that of the steel specimen respectively.  