木星、土星、天王星和海王星。这些都是气体行星，是太阳系的四个重量级。但曾经存在第五个行星吗？

Jupiter, Saturn, Uranus, and Neptune. Those are the gas giants, the four heavyweights of the solar system. But was there once a fifth?

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去年它开设了第四个空间站，目前正在推进建造第五个空间站的计划。

It opened its fourth station last year and is pressing ahead with plans to build a fifth.

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她说：“ 我看了他一会儿，我儿子是他推倒的第四个或第五个孩子。”

"I'd watched him for a little while and my son was the fourth or fifth child he'd shoved," she says.

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If we take nitrogen, we've got N2, and we've got one, two, three, four, five.

比如说氮，我们得到了氮气，我们有一个，两个，三个，四个，五个。

麻省理工公开课 - 固态化学导论课程节选

So we have 4 plus 5, but we're actually not done yet, because it's c n minus, so if we have minus, we actually have an extra electron in our molecule.

我们有四个加上五个，但是我们实际上还没做完，因为这是个负离子，所以如果我们有这个负号，那么我们的分子实际上还有一个额外的电子。

麻省理工公开课 - 化学原理课程节选

The good news is the elements in any one spot in a hash table are likely to be a small number, three, four, five.

好的一点是在哈希表中,任何一个存贮点上的元素数据是很小的,三个，四个，五个。

麻省理工公开课 - 计算机科学及编程导论课程节选