我们都知道应该一天刷两次牙并有规律地用牙线洁牙。

Of us know that we need to brush our teeth twice-a-day and floss on a regular basis.

我们都知道应该一天刷两次牙并有规律地用牙线洁牙。

All of us know that we need to brush our teeth twice-a-day and floss on a regular basis.