Both grooves could then be played at the same time using two needles.

这样两个沟槽可以同时演奏，通过使用两个针头。

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In 1877, he created a machine with two needles: one for recording and one for playback.

1877年时，他创造了一个内附两只唱针的机器：一只用来记录，而另一只用来播放。

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When it is used for sterilization, it takes same operation step as the fourth step; two needles will produce ozone and negative ions.

用于杀菌灭毒，与第四步打火操作步骤同，两针将产生臭氧和负离子。

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Two more needles were discovered, including one found by a federal air marshal.

CNN: STORY HIGHLIGHTS

Two of the needles were found by passengers, she said, at which point Delta told all 18 flights from Amsterdam to stop serving the sandwiches.

CNN: STORY HIGHLIGHTS

And needles were even sometimes used as weapons, usually thrown at their victims, although two inch-long needles called fukibari were carried in the mouths of ninjas and spat into enemies' faces.

FORBES: No. 13 The Needle