用微积分是可以的；不知直接证明容易不

来源: 乱弹于 2015-02-16 17:30:05 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

WENXUECITY.COM does not represent or guarantee the truthfulness, accuracy, or reliability of any of communications posted by other users.