慢速英语:美国宇航局太空船捕捉到的小行星样本远远超过预期

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asteroid – n. objects made of rock and metal which orbit the sun, but are smaller than planets

sample – n. a small amount of something that gives you information about the thing it was taken from

capsule – n. the part of a spacecraft that carries people

of the essence – phr. highly important

precisely – adv. exactly

preserve – v. keep something the same or prevent it from being damaged of destroyed