Rainbows sometimes appear as two concentric bows with the inner one called the primary bow and the outer one the secondary bow.

彩虹有时会以两条同心圆弧形态出现。内弧称为主虹，外弧称为副虹或霓。

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He spent the past year plotting a primary run against Giuliani, only to bow out when Pataki told him to.

CNN: Rudy's soulful exit