While electricity exists as separate charges, like the plus and minus of a battery, magnets always come in a joined pair;

电可以作为分开的电荷存在，比如说电池的正极与负极，而磁则总是要成双成对地出现。

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A crunch could come in the next few months, as foreigners gather for a pair of summits on Afghanistan, first in Istanbul in November, then in Bonn in December.

接下来几个月可能出现危机，因为许多外国人会就阿富汗问题参加两个峰会，第一个是于11月在伊斯坦布尔召开，随后是于12月在波恩。

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Sometimes a mail steamer would come in, and Captain Nichols, having scraped acquaintance with the timekeeper, would succeed in getting the pair of them a job as stevedores.

有时候一艘邮轮开进港，尼柯尔斯船长同雇用计时员攀上交情，会给两人找个临时装卸工的活儿。

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If I do come in 2012, I will invest in a pair of decent black snow boots, elegant enough to wear with suits and skirts, at least during the day.

FORBES: Exclusion and Inclusion at Davos

And because chromosomes and therefore genes come in pairs, and mutations occur independently in each gene of the pair, the two versions of a particular gene in any asexual line will gradually diverge, becoming more and more different from one another.

ECONOMIST: The longest ��headache�� ever

They also come in three pairs, one member of each pair being measurably heavy (though lighter than a quark) and one being of minuscule mass.

ECONOMIST: Particle physics makes sense, but it assumes too much