Only in a flat universe does space obey all the standard geometry-class rules-the angles of a triangle add up to exactly 180 degrees and parallel lines never meet.

只有在平坦的宇宙中，空间才符合标准的几何规律——三角形的内角和精确地等于180度，平行线永远不相交。

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Only in a flat universe does space obey all the standard geometry-class rules-the angles of a triangle add up to exactly 180 degrees and parallel lines never meet.

只有在平坦的宇宙中，空间才符合标准的几何规律——三角形的内角和精确地等于180度，平行线永远不相交。

youdao