偶然撞上; 偶然遇见
1. 碰撞;同...冲突：knock out 敲空;(拳击中)击倒 | knock up against 碰撞;同...冲突 | know about 了解,知道...的情况
2. 碰撞：knock under to 屈服 | knock up against 碰撞 | knock up 筋疲力尽
3. 碰撞; 同...冲突; 偶然碰见：knock off 敲掉; 击倒 下班休息; 罢工 | knock up against 碰撞; 同...冲突; 偶然碰见 | knock up 敲门叫醒 赶做;