动词中文翻译
中文翻译：变硬
同义词：
['harden', 'stiffen', 'strengthen']
例句：
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1.The old man is toughening his muscles to prepare for a marathon.
老人正在努力锻炼身体，为马拉松做准备。
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2. The car was toughened by the cold weather.
汽车被寒冷的天气给硬化了。
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3. The steel beams were toughened to withstand the weight of the building.
这些钢梁被硬化以承受建筑物的重量。