all at once   (TTS發音)

1. all of a sudden；suddenly；unexpectedly突然；出乎預料

    All at once they found themselves surrounded by the enemy. 他們突然發現自己被敵人包圍了。

    All at once she decided she wasn't going. She didn't explain why. 她突然決定不去了，她沒有講明理由。

    All at once we heard a shot and the soldier fell to the ground. 突然我們聽到槍聲，接著士兵就倒下去了。

2. at the same time；together同時；一起

    When he heard the news， he was happy and sad all at once and didn't know what to do. 聽到這消息，他悲喜交集，不知所措。

    She couldn't tell them more about the accident. Everything just seemed to have happened all at once. 她不可能向他們講述更多的事情，一切都似乎是同時發生的。

3. without delay馬上；即刻

    We just can't decide such an important thing all at once. 我們只是不能馬上決定這樣一件重要的事情。