“一掌”的英语可以翻译为：fisticuff...

她慢慢挥起右手,朝他重重地击了一掌.She swung a slow, heavy right hand at him.他转过身来,我对着他的头部侧面就是一掌.He turned and I slapped him right upside the head.她一掌打掉了他手中的钱.She hit off the money in his hand with one blow....