The key stratum is not easy to cave, but once it is caved, there will be a sudden collapse of a rather thick stratum.

关键层较难崩落，但在崩落时具有突发性，会产生较大厚度岩层的突然垮塌。

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The conventional wisdom holds that politicians must be packaged as feeling family types, rather than thick-skinned, sharp-elbowed machines dedicated to self-advancement.

ECONOMIST: Lexington

He is sweet, dedicated, and rather sexy with that thick accent.

BBC: X-Men 2: Your views

So it is ditching prescriptive standards which say, for example, how thick a door must be rather than merely how long it should be able to withstand a fire.

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