I was wakened by a knock at the door.

敲门声把我吵醒了。

《牛津词典》

They were interrupted by a knock at the door.

他们被敲门声打断了。

《牛津词典》

They heard a knock at the front door.

他们听到前门有一敲门声。

《柯林斯英汉双解大词典》

"When I was sleeping I heard a knock at my door, and I opened my door and two men were there and gave me a pouch and said, 'A gift for you.'" The prosecutor asked Campbell if she knew who the gift was from.

VOA: standard.2010.08.05

Mr Demirsay, known locally as Sharif, was stabbed after answering a knock at the door.

BBC: Serafettin Demirsay

The blinds were shut, and a dog barked when there was a knock at the door.

WSJ: Bond Set at $8 Million in Cleveland Kidnap Case

We had just begun the meal when there was a knock at the door.

NEWYORKER: Amundsen