What's more, they can be used to attack a candidate's opponent, this practice is known as negative ads.

更重要的是，它们可以被用来攻击候选人的竞争对手，这种做法被称为负面的广告。

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Kate argued vehemently against using these ads, but she was overruled by Vince. Now she's sure she was right; negative ads rarely work.

凯特曾强烈反对用这些广告，但她的意见被文斯驳回，现在她确信自己是正确的，负面的广告不起什么作用。

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But with both sides firing off negative ads at each other, experts say it is hard to know whether people are paying attention or to gauge the impact.

虽然双方展开了负面广告大战，但是专家们说，很难确定人们是否注意这类广告，也很难衡量这些广告的影响。

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With 9 percent of those polled still undecided, negative ads are flooding Missouri's airwaves.

CNN: Missouri heavyweights slug it out in heated Senate race

And the other side is preparing to unleash just a barrage of negative ads.

WHITEHOUSE: The White House

But Bumpers easily defeated Huckabee after a nasty campaign that featured negative ads and character attacks.

NPR: First Race Teaches Huckabee to Trust His Instincts