She is tough, unwilling to take no for an answer.

她很难对付，不答应不肯罢休。

《柯林斯英汉双解大词典》

She is tough, proud, smart, cynical, and like eighty-years old.

她坚强，骄傲，聪慧，愤世嫉俗，像80岁得老太太。

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These were sentiments expressed by some voters. "She has enough experience and she is tough enough."

一些选民说：“她有足够的经验，而且也很强悍。”

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She exudes a sense that she is tough enough to defend America's interests.

ECONOMIST: The candidates: Hillary Clinton

She is tough as nails.

CNN: STORY HIGHLIGHTS

Speaking after Ms Harris at the fundraising event in California on Thursday, Mr Obama said she was "brilliant and she is dedicated and she is tough, and she is exactly what you'd want in anybody who is administering the law and making sure that everybody is getting a fair shake".

BBC: Obama sorry over Kamala Harris 'good-looking' comment