域名系统分类中的最高层级。
The highest level of subdivisions with the domain name system.
正式名称为甲型流感(H1N1)病毒的危险层级已提高到最高层级六。
The threat level presented by the virus - officially known as influenza a (H1N1) - was raised to phase 6, the highest level.
在初级阶段你会进步得很快，然而一旦著了迷，就必须加倍努力，要达到最高层级或终极目标却遥遥无期。
you rise rapidly through the first levels but, once hooked, have to work harder and harder with no final level or goal in sight。
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