to be short

基本解释

But why does the time frame have to be short?
那我要问，为什么是“短期”的才能有效？
"If you must have it, it needs to be short and well groomed," he cautions.
他警告说：“如果你非要这样做的话，也要确保胡须要短而整齐。”
One of the things that everyone agrees about methane on Mars is that it has to be short-lived.
大众普遍认同的一件事是火星上的甲烷的寿命极短。

And this may be cool enough to keep foods fresh, at least for a short time.
If we have a high frequency, what about the wavelength, long or short? All right. Good. So we should always be able to keep these relationships in mind.
如果频率高，那波长是长还是短？,好，不错，我们要记住这些关系,类似的。
麻省理工公开课 - 化学原理课程节选
There's a Midterm. That will be a short answer test that's intended to give you a chance to show how diligently you've been reading and coming to class.
我们会有一个期中考，会有一张简答问卷,目的是能够让你们表现出,你们的勤劳，用功阅读和按时上课。
耶鲁公开课 - 现代诗歌课程节选

Simple exclusion of the opinion of front line people has long been proven to be short-sighted.
FORBES: Business Aviators - Is that all they are, or should be?