首先，这些武器应当只在遭受核袭击后反击时才使用。其次，这些武器的拥有必须是一种临时的应急手段。

First, the weapons should be intended for use only in retaliation after a nuclear attack. Second, the possession of the weapons must be a temporary expedient.

《柯林斯英汉双解大词典》

其次，堵车时汽车产生了更多的废气，进一步加剧了空气污染。

Secondly, cars in traffic jams produce more exhaust that exacerbates air pollution.

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如今该公司在寻找翻译时，首先考虑其专业知识，其次才看语言是否匹配。

Now the firm searches first for technical expertise and then for the language match.

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