词典词条 · 问答

knock

knock at/knock on

说明

knock at/knock on

核心问题

（1）Just then there was a knock on the door.

(2) He was just falling asleep when there was a loud knock at the door.

请问 knock at 与 knock on 哪个用法正确?

词典解答

两种用法都是正确的。