The son silently took a flail and they began threshing with four flails.儿子也开始悄悄乘枷脱粒四枷....

v.鞭打( flail的第三人称单数 )，用连枷脱粒，（臂或腿）无法控制地乱动，扫雷坦克...

flails的音标：...