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Passage One
短文一
Stress is often depicted as negative, but research shows that moderate amounts of it can be beneficial for your brain and your body.
压力通常被描述为消极的，但研究表明，适量的压力对你的大脑和身体都有好处。
First, the benefits for the brain.
首先，对大脑的好处。
Studies have shown that short periods of stress can actually bolster cognitive functioning.
研究表明，短期的压力实际上可以增强认知功能。
Researchers discovered that placing rats in a stressful situation for just a few hours doubled the growth of new brain cells.
研究人员发现，将老鼠置于压力环境中仅几个小时，新脑细胞的生长就会翻倍。
The rats also did better on a memory test later on.
老鼠在随后的记忆测试中也表现得更好。
Scientists think the same thing happens in humans.
科学家认为同样的事情也发生在人类身上。
But, how does stress improve memory?
但是，压力是如何提高记忆力的呢?
It's simple.
这很简单。
When your brain cells multiply, your memory can improve,
当你的脑细胞繁殖时，你的记忆力就会提高，
viewed from a biological perspective, this makes sense because animals that are better at remembering dangerous situations can avoid them in the future.
从生物学的角度来看，这是有道理的，因为善于记住危险情况的动物可以在未来避开它们。
If an animal encounters a predator and escapes, for example, it's important to remember where and when that encounter happened.
例如，如果一只动物遇到了捕食者并逃脱了，记住这种遭遇发生的时间和地点是很重要的。
Experts assert that the same principle applies to humans.
专家们断言，同样的原则也适用于人类。
Now, let's turn to how stress benefits the body.
现在，让我们转向压力对身体的好处。
This may come as a surprise to laymen, but experts say that stress can keep you from getting sick.
这可能会让外行人感到惊讶，但专家说，压力可以让你远离疾病。
Scientists concede that chronic stress can make you more prone to illness,
科学家们承认，长期的压力会让你更容易生病，
but research shows that short periods of stress can actually provide some protection against getting sick because it increases your immune functioning.
但研究表明，短期的压力实际上可以提供一些预防生病的保护，因为它增强了你的免疫功能。
One study shows that rats that experience brief stress had a surge of immune cell response, which makes the immune system better prepared to fight illness.
一项研究表明，经历短暂压力的老鼠的免疫细胞反应激增，这使得免疫系统更好地准备对抗疾病。
For humans, there is even evidence that experiencing stress before getting vaccinated could help make vaccines more effective.
对于人类来说，甚至有证据表明，在接种疫苗前经历压力有助于使疫苗更有效。
Questions 9 to 11 are based on the passage you have just heard.
请根据你刚听到的短文回答问题9到问题11。
Question 9: What did researchers discover about rats placed briefly in a stressful situation?
问题9:研究人员将老鼠短暂地置于压力环境中，发现了什么?
Question 10: Why do people tend to have clearer memories of dangerous situations they have encountered?
问题10:为什么人们对遇到的危险情况有更清晰的记忆?
Question 11: What do scientists believe chronic stress can do?
问题11:科学家认为长期压力会造成什么?
