wake-up call

复数：wake-up calls

n.

a warning to take action concerning something that was overlooked or neglected

a telephone call that you request be made a specific time in order to wake you up at that time (especially in hotels)

1. I set an early wake-up call for tomorrow morning.
   我为明天早晨安排了一个早晨叫醒电话。
2. The recent financial crisis served as a wake-up call for the government to reform the economy.
   最近的金融危机为政府改革经济提供了警示。