网站首页  英汉词典

请输入您要查询的英文单词：

　

单词 Necessary cause
释义

Necessary cause

原声例句
国富论（一）

To complain of it, is to lament over the necessary cause and effect of the greatest public prosperity.

抱怨它，就是哀叹最大的公共繁荣的必要因果关系。

英语百科

Necessity and sufficiency

The sun being above the horizon is a necessary condition for direct sunlight; but it is not a sufficient condition as something else may be casting a shadow, e.g. in the case of an eclipse.
That a train runs on schedule can be a sufficient condition for arriving on time (if one boards the train and it departs on time, then one will arrive on time); but it is not always a necessary condition, since there are other ways to travel (if the train does not run to time, one could still arrive on time through other means of transport).
Consider two logical statements S and N, such that S is sufficient for N (if S is true, then N must also be true). Figuratively, if we are within S then we are within N. It follows that S cannot be true unless N is true – i.e., that N is a necessary condition for S.

In logic, necessity and sufficiency are implicational relationships between statements. The assertion that one statement is a necessary and sufficient condition of another means that the former statement is true if and only if the latter is true. That is, the two statements must be either simultaneously true or simultaneously false. In ordinary English, 'necessary' and 'sufficient' indicate relations between conditions or states of affairs, not statements. Being a male sibling is a necessary and sufficient condition for being a brother. Fred's being a male sibling is necessary and sufficient for the truth of the statement that Fred is a brother.
随便看

　

英汉网英语在线翻译词典收录了3779314条英语词汇在线翻译词条，基本涵盖了全部常用英语词汇的中英文双语翻译及用法，是英语学习的有利工具。

　

Copyright © 2004-2024 encnc.com All Rights Reserved
更新时间：2025/6/21 18:22:42