**"All at Once" 句子释义和用法**

**中文解释：** "All at once" 是一个英语短语，通常用来表示某个事件或情况突然发生，或者同时发生。它强调的是瞬间性和同步性。

**英文解释：** "All at once" is an English phrase that typically indicates something happens suddenly or simultaneously. It emphasizes the immediacy and simultaneity of an event or situation.

**用法示例：**

1. **中文：** 当他听到这个消息时，所有的快乐都一下子消失了。

   **英文：** All at once, all his happiness vanished when he heard the news.

2. **中文：** 乌云密布，大雨倾盆而下，所有的一切都在一瞬间变得模糊不清。

   **英文：** The sky grew dark, and the rain poured down all at once, making everything blurry in an instant.

3. **中文：** 她在舞台上一开口唱歌，所有的目光都集中在了她身上。

   **英文：** As she began to sing on stage, all eyes were upon her all at once.

4. **中文：** 火车突然加速，所有的行李都向前滑去。

   **英文：** The train accelerated abruptly, and all the luggage slid forward all at once.

**同义词辨析：**

1. **Suddenly**: 这个词也表示事情突然发生，但不强调同步性。例如："Suddenly, he remembered an important appointment."

2. **Instantly**: 与"All at once"相似，"Instantly"强调事件的即时性。例如："The lights went out instantly when the power supply failed."

3. **Simultaneously**: 这个词更侧重于多个事件在同一时间发生。例如："The explosions happened simultaneously across the city."

4. **In a flash**: 这是一个形象的表达，意味着事情在极短的时间内发生。例如："The thief disappeared in a flash when the alarm sounded."

5. **All together**: 虽然这个词组有时也可表示同时发生，但它更常用于强调集体或整体。例如："Everyone arrived all together for the meeting."