tap

我感到背上被轻轻拍了一下。

I felt a ___tap on my back.

热水龙头在左边。

The hot ___tap is on the left side.

门上传来轻轻的敲击声。

There was a light ___tap at the door.

使用后请关掉水龙头。

Please turn the ___tap off after use.