Dave: How many times do you brush your teeth every day,David?

你一天刷几次牙，大卫?

David: Once.

一次。

Dave: No wonder you often get a toothache,brush your teeth twice a day and don't eat too much candy.

难怪你老是牙疼。一天刷两次牙，还有别吃太多糖果。

David: OK,I will.

好，我会的。