拿根正态曲线（钟型曲线）50-100 是A, 30-42.5是B，20-27.5是C。。。当然A 概率最高。

来源: 数字证于 2013-06-16 15:57:28 [旧帖] [给我悄悄话] 本文已被阅读：次

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