他承认，存在非常小的可能性，这些预期会降临地球的未来人民，事实上可能不会存在，例如地球可能被陨石撞毁。
He admits there is a slim chance these prospective generations will not in fact exist: the earth might be wiped out by a meteorite, for example.
如果飞机得不到充分的动能，就只能在地面上滑行，不会飞起来，或者会撞毁。
If the plane doesn't get enough momentum, it just rolls around on the ground and never takes off — or it might just crash.
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