toughens
v.
（使某物[人]）坚韧，坚强，强硬( toughen的第三人称单数 );
例句:
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The new law toughens up penalties for those that misuse guns.
新法对滥用枪支的处罚更为严厉。
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He thinks boxing is good for kids, that it toughens them up.
他认为拳击对小孩子有好处，可使他们变得坚强。
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They believe that participating in fights toughens boys and shows them how to be men.
他们认为参与打架会使男孩子变得坚强，教会他们怎样成为男人。
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But you get used to it and it kinda toughens you up a bit.
来自BBC
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It also toughens the kids up you see, and prepares them for a priviledged life where emotion is the preserve of the underclasses.
来自BBC