knock on基本解释
敲击；<非正>（使）增加；不停地工作；取消

网络释义
1. 敲打
2. 撞击撞出
3. 挥击球

knock on的用法和例句
About 20 minutes later I heard a knock on my door .
大概20分钟之后，我听到敲门声。

Mr kreutzer explains how his workers just pop up and knock on my door .
克罗伊策先生解释说，他的员工会“突然冒出来，敲我的房门”。

Later that night there was a knock on the door of the village tailor .
那天晚上，村子里的裁缝听到了敲门声。

Their job is to listen out for offensive noises and knock on the door of guests who snore too loudly .
他们的职责是监听恼人的鼾声，如果声音过大就去敲门。