But why is the feeling of being on an emotional roller coaster so common among teens?

但为什么青少年普遍感觉他们的情绪就像是坐过山车一样，时好时坏呢？

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I was feeling under the weather. B: Oh, did you have that cold that everyone's had? A: I think so. Under the weather is an extremely common expression, meaning a little ill or sick.

b：哦，你是不是感冒了A：我也这样认为我感觉不舒服是一个极其普遍的词组，意思是生了点小病。

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The most common symptom is feeling tired because the body is not receiving enough oxygen.

最常见的症状是缺氧而造成的疲乏。

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"The common feeling is that by 2020 virtual worlds will be as widespread as the World Wide Web is now, " states Booker.

CNN: Virtual worlds: The next Facebook?

The fact that this last feeling is so common in depression explains why being "stressed out" is such a good marker for major depression.

CNN: Stress has taken over: How can I turn my mind off?

Temporary numbness or loss of feeling at the site of the incision is fairly common in face-lifts and tummy tucks, though it's rarely permanent.

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