all of a sudden
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突然, 忽然
in an unexpected or abrupt manner
- All of a sudden, the storm rolled in, darkening the sky.
突然，风暴来临，天空变暗了。
- He felt dizzy all of a sudden and had to sit down.
他突然感到头晕，不得不坐下。
- All of a sudden, the dog started barking loudly.
突然，狗开始大声吠叫。
- She burst into laughter all of a sudden, surprising everyone around her.
她突然大笑起来，让周围的每个人都感到惊讶。
- All of a sudden, the power went out, leaving the house silent.
突然停电了，房子里一片寂静。
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