Failing to be observant while walking or driving can be life threatening.

走路或开车时不注意观察可能会危及生命。

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You should be observant of the traffic rules.

你应该恪守交通规矩。

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Whatever you do, be observant of what is going on around you.

无论你在做什么，对于你周围所发生的一切要善于观察。

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And security officials are encouraging passengers to be observant and report any suspicious activity.

VOA: standard.2009.12.26

In fact, you should be keenly observant from the time you arrive until you say your goodbyes.

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You would have to be religiously observant and austere yourself, then, to really seek a ban on Christmas.

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He writes in an endearing first person voice that can be both wryly observant and objectively fair at once.

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