本章不演示双因子认证有两个原因。
I don't show two-factor authentication in the book for two reasons.
试验选用双因子设计方法,采用不同的配方进行皮蛋加工。
The method of double-factor design is adopted. And the preserved eggs are processed by using different ingredient.
一个双因子临界图是一个砖块 ,如果它是 3-连通的 。
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