He got a nasty knock on the head.
他头部遭到重重一击。
There was a sharp knock on the door.
敲门声大作。
No sooner had I sat down than there was a loud knock on the door.
我刚坐下就有人大声敲门。
He went up the garden path to knock on the door.
他穿过花园小径去敲门。
If you haven't made an appointment, take pot luck and knock on the door
如果你没有预约，就敲门试试运气吧。