One is a quick-acting "rescue" medicine taken when needed to stop asthma symptoms.

VOA: special.2009.07.28

So, our bodies are capable of making antibodies that are tuned for all the potential antigens that we come into contact with, That's amazing that we have this capacity to respond and you respond only when needed.

所以 我们的身体具有制造抗体的能力,这些抗体对于各种潜在抗原具有特异性,我们具有只在需要时做出,免疫反应的能力 这太让人惊叹了

耶鲁公开课 - 生物医学工程探索课程节选

I just needed one more credit hour when I was going to school,

我上学的时候就差一个学分，

攀岩的刺激 - SpeakingMax英语口语达人

The president also says he will send the military into battle only when needed, and will give them the necessary training and equipment.

VOA: standard.2009.05.23

We did that during the Great Depression, when it suddenly seemed like we really needed to do something.

是在大萧条时期开始实行的，因为当时我们突然发现,确实该做点什么了。

耶鲁公开课 - 金融市场课程节选

She says the only work needed once beets have been thinned is weeding and, when the weather is dry, a weekly watering.

VOA: special.2010.03.02

When this movie came out twenty years ago they needed a character to play a gay man.

0年前这部电影上映时,他们需要一个人扮演一个同性恋男人。

耶鲁公开课 - 心理学导论课程节选

Verrocchio told his students that they needed to understand the body's bones and muscles when drawing people.

VOA: special.2010.09.15

So, this is the kind of immune response that gets activated only when it's needed.

所以 这是一种在需要时,被激活的免疫反应

耶鲁公开课 - 生物医学工程探索课程节选

Water is needed for cooling the body on hot days, and when we are working or exercising.

VOA: special.2010.07.27

And we also, when we solved or we looked at the solution to that Schrodinger equation, what we saw was that we actually needed three different quantum numbers to fully describe the wave function of a hydrogen atom or to fully describe an orbital.

此外，当我们解波函数,或者考虑薛定谔方程的结果时，我们看到的确３个不同的量子数,完全刻画了氢原子,的波函数或者说轨道。

麻省理工公开课 - 化学原理课程节选

"It's times like that when you have such great pride in Americans, when you see somebody do something like that for a smaller sport, certainly a prominent sport, where they needed that funding.

VOA: standard.2010.02.21

But they tried to do that only when they needed to do so to keep their absolute control.

不过他们只有需要保持绝对权力时,才会这么做。

耶鲁公开课 - 新约课程节选

"We found that easier access to emergency contraception did help women use the pills more quickly when it was needed, and they used it more often, but despite that increased use and faster use, it didn't reduce rates of unintended pregnancy."

VOA: standard.2010.03.22

"Well,actually I was scheduled to work this morning," . "When I got up at 5:30, I saw on the news that they needed a lot of help, and I called into my job and said I needed to take a short day vacation, because I needed my son to be a part of what was going on."

VOA: standard.2010.01.18