His glasses fell down on the floor and broke up.

他的眼镜掉在地上摔碎了。

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　　动词词组break up，意思是“终止，结束或打碎、拆散”，英文的解释是，To scatter or disperse, to cease to exist as a unified whole（分散，破碎，不再是完整的）。
　　例句：
　　The crowd started to break up when the night fell.
　　天快黑时人群开始散开了。
　　Their marriage broke up. 他们的婚姻破裂了。