all of a sudden   (TTS發音)

quickly， without advance warning 突然

    It started out to be a beautiful day. Then， all of a sudden，it became cloudy and began to rain. 開始，天氣晴朗。後來，突然多雲而且開始下雨。

    All of a sudden a man burst out of the building， and made off down the road. 突然，一個人從大樓裡衝出來，沿著大路逃跑。