利用幂级数的方法，对三阶线性离散系统进行时域分析，其方法不仅可以研究线性非时变离散系统，而且还可以研究线性时变离散系统。

This paper presents the time domain analysis of three orders discrete system by power series, which can study not only the time invariant system, but also the time variant system.

youdao

youdao

经济衰退时，消费者有可能会缩减玩具等非必需品的消费。

In a recession, consumers could be expected to cut down on nonessentials like toys.

《柯林斯英汉双解大词典》

So, he writes: To the psychologist alone can such questions occur as: Why do we smile when pleased and not scowl?

他这样写到：,对哲学家本身说,会出现这些问题：,为什么开心时我们微笑而非皱眉？

耶鲁公开课 - 心理学导论课程节选

Because, for the purposes of this class, I'm going to reserve the word "Soul" for the immaterialist conception of the mind.

为了讲课的需要,我会将"灵魂"这个词,留到讲心灵的非物质性概念时再用

耶鲁公开课 - 死亡课程节选

You might have thought before we started talking about molecular orbital theory that non-bonding was the opposite of bonding, it's not, anti-bonding is the opposite of bonding, and anti-bonding is not non-bonding.

你也许在我们讨论分子轨道之前,就想过非成键时成键的反面，它不是，反键才是成键的反面，反键不是非成键。

麻省理工公开课 - 化学原理课程节选