这些动词在变形为ing形式时需双写词尾bidding, banning, betting, blogging, begging, digging, fitting, hopping, hitting, hugging, jogging, kidding, nagging, nodding, getting, forgetting, cutting, letting, begeinning, skipping, dubbing, putting, patting, spitting, skipping ,sitting,running,swimming
重读闭音节 并且后面只有一个辅音字母 这时要双写这个辅音字母 在加ed.（x除外）
如 stop stopped 单音节词都是重读音节