In order to make a nuclear explosion, the critical mass must come together within a fraction of a millionth of a second.

为促成一次核爆炸，临界质量必须在一百万分之一秒内聚集在一起。

《柯林斯英汉双解大词典》

The bomb must explode within less than a millionth of a second.

那枚炸弹必须在百万分之一秒内爆炸。

《柯林斯英汉双解大词典》

Within each phase, you must achieve a major milestone via the execution of one or more micro iterations before the next phase can begin.

在每个阶段中，您必须在下一个阶段开始之前，通过执行一个或多个微迭代来实现一个主要的里程碑。

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Hatoyama is expected to be formally elected prime minister in a special session of parliament, which must be held within 30 days.

VOA: standard.2009.08.31

Members must be picked within a month and the panel must submit a proposal to Congress and the White House within six months after that.

FORBES: Fiscal Cliff Deal Repeals CLASS Act, Creates Long-Term Care Commission

The bill, dubbed the Fair Pay Restoration Act, would have rolled back a 2007 Supreme Court ruling that a person who claims pay discrimination must file a complaint within 180 days of that discrimination taking place.

CNN: McCain calls for $300 million prize for better car battery

Although the term Geoparks does not have a specific legal status, the important monuments and sites within a Geopark must be protected in every case, under local, regional or national legislation.

UNESCO: Global Geoparks Network