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(单词翻译:双击或拖选)
You’re a polar explorer and you’ve just reached the north pole. The huskies are yapping, the cameras are ready and you’re just about to unfurl the flag when, all of a sudden, the north pole becomes the south pole. Imagine your chagrin1. Okay, so it doesn’t really happen that fast, but it’s true that in the past the earth’s magnetic poles have switched places. In fact, it seems to happen roughly every 250,000 years or so. How do we know this? When lava2 is in its molten state, the atoms in it can move around fairly easily. At this time some atoms, like iron, will align3 themselves with the earth’s magnetic field in a recognizable way. Then, as the lava solidifies4 into rock, these little compasses get frozen in position. It’s like writing your name in wet cement.
1 chagrin | |
n.懊恼;气愤;委屈 | |
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2 lava | |
n.熔岩,火山岩 | |
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3 align | |
vt.使成一线,结盟,调节;vi.成一线,结盟 | |
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4 solidifies | |
(使)成为固体,(使)变硬,(使)变得坚固( solidify的第三人称单数 ); 使团结一致; 充实,巩固; 具体化 | |
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