Attacks on Internet sites and infrastructure, and the compromise of secure information, pose a particularly tricky problem because it is usually impossible to trace an attack back to its instigator.

因为通常不可能追踪到攻击者，对互联网站和网络基础结构的攻击，及其对安全信息的危害，是一个异常棘手的问题。

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To help you tie these techniques back to the classes of attack just presented, for each technique we will include the following graphic.

为了帮助您将这些技术与刚才提到的攻击类别联系起来，我们将使用以下图形解释各种技术。

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You must try to hold back German attack.

你必须设法阻止住德军的进攻。

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Should Mexico attack, Taylor and his men were to strike back as hard as possible.

VOA: special.2009.02.19

So how would we go about solving this problem if I told you not only was there a maximum weight, but there was a maximum volume. Well, we want to go back and attack it exactly the way we attacked it the first time, which was write some mathematical formulas.

有些时候两个都重要,所以如果我告诉你这里不仅有,最大重量还有最大容量，我们应该怎么解决这个问题呢？,好了，我们想回过来然后,和第一次一样看看这个问题。

麻省理工公开课 - 计算机科学及编程导论课程节选

When they reported back three days later, General Lee knew exactly where he would attack.

VOA: special.2009.09.17

"We are afraid to return to the camp, because armed men may come back to attack us, " Fatima Adam Badaui, a woman from the Kassab camp, told UNAMID.

CNN: STORY HIGHLIGHTS

Plus, blocked shots often are collected by the penalty killers and sent down the ice with impunity, killing precious seconds until the power-play team can get it back and attack again.

WSJ: Rangers Nab Shootout Win

But Munster held firm and when they went back on the attack just after the hour Pelous, who had just come back onto the pitch, was again penalised, this time for not rolling away in the tackle, and O'Gara kicked Munster back into the lead.

BBC: Munster 16-13 Toulouse