The Thirty Meter Telescope's massive primary mirror has 492 segments, all perfectly aligned to form a 30-meter (98-foot) light-collecting surface.

30米望远镜的巨型主镜分割成了492块，完美地排列从而形成30米(98英尺)的集光面。

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But it had buoyed to the surface just as the squall sprang up, and with 30-knot winds and four-foot swells that splashed over the stern, it was too dangerous to retrieve the sub.

但潜艇刚刚浮上水面，暴风就凶猛来袭，30节的风速和足有四英尺高的巨浪就扑到了船上。

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Growing to about a foot (30 centimeters) long, blind snakes act a lot like worms, burrowing under the surface of every continent except Antarctica.

除了南极洲，在地球上的其他各大洲都可以见到盲蛇。 它们钻入土壤中，就像一条蠕虫一样，而它们的身长也只能达到一英尺（30厘米）。

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He stepped foot on the surface right after Neil Armstrong.

VOA: special.2010.04.28

If you dig your foot into the surface and remove some of the clay, you will notice that the underlying surface is a hard rubber-like mat.

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Eugene Cernan, who is with us today, the last man to set foot on the lunar surface.

CNN: Bush: 'It is time for America to take the next steps' in space

When the larva grows to around 300 microns (roughly one-third of a millimetre), it extends its foot and seeks a suitable surface on which to set.

ECONOMIST: A dozen ocean-cleaners and a pint of Guinness, please