Birds sometimes chatter to each other to warn of danger.

鸟儿有时互相啁啾，通报危险。

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I warn him of the danger.

我警告过他说有危险。

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Warn everyone of the danger.

警告所有人注意危险。

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He got a metal shovel and hit the stone sides of the house so that the noise would warn the birds and animals of danger.

VOA: special.2010.03.20

Other products warn drivers if they are falling asleep or in danger of an accident.

VOA: special.2010.01.08

According to Dr Sinclair's theory, which he calls xenohormesis, animals rely on such botanical stress signals to give them extra information about their own environments, in the same way that the alarm calls of one species warn others of danger.

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Critics warn of the danger of so many young people having their formative experiences of alcohol without the supervision of bar staff and bouncers.

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Twitter is emphasising that it acted rapidly to warn people the moment that it spotted the danger - but there is still little information about the nature of the attack or why just one small section of users is in danger.

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