服务员少收了我咖啡的钱。

The waiter ___undercharged me for the coffee.

这家餐厅的账单出错了，他们少收了我们20元。

The restaurant made a mistake on our bill and ___undercharged us by 20 yuan.

如果手机电池充电不足，它的续航时间会明显缩短。

If the phone battery is ___undercharged, its battery life will be significantly shorter.