Parallel straight lines are straight lines which, being in the same plane and being produced indefinitely in both directions, do not meet one another in either direction.

平行直线是在同一平面内的直线，向两个方向无限延长，在不论哪个方向它们都不相交。

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A two-dimensional model of such a universe would look like a sphere. It's impossible to have parallel geodesics (straight lines on a curved surface) — the two lines will cross at some point.

这样的2维宇宙模型就像是球体，不可能出现平行的测地线(测地线是曲面上的直线)——两直线必然在某点相交。

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In this illusion although the lines appear to be bent they are actually perfectly straight and actually parallel.

在这个错觉中，虽然线条看起来是弯曲的，但实际上却是笔直的，并且实际上是平行的。

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