服务只有被消费了才有用；所以，要规定服务的效用，最好的方式就是描述消费者对它们有何期望。
Services are useful only insofar as they are consumed, and so the best way of specifying their usefulness is to describe what consumers expect of them.
有用性可能会有益于效用的增加，但是风格、潮流、想法同样可以。
Usefulness might contribute to utility, but so does style, fashion, or even whimsy.
这使set-user-ID（非根）程序能够放弃它的所有用户特权，执行一些非特权操作，然后恢复原来的有效用户ID。
This allows a set-user-ID (other than root) program to drop all of its user privileges, do some un-privileged work, and then re-engage the original effective user ID in a secure manner.
第二，固定和体现在人身上的效用：在此情况下，劳动用于使人具备能使他们对自己和别人有用的品质。
Secondly, utilities fixed and embodied in human beings; the labour being in this case employed in conferring on human beings, qualities which render them serviceable to themselves and others.
效用经常与有用性相混淆，这是对概念的误解。
Utility is sometimes confused with usefulness, which is a misunderstanding of the concept.
效用经常与有用性相混淆，这是对概念的误解。
Utility is sometimes confused with usefulness, which is a misunderstanding of the concept.
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