Yawning (打哈欠) is something we all do — maybe because we’re bored carrying out boring tasks or because we’re tired. Sometimes, just seeing other people yawn can set you off.

According to BBC, new research suggests it might because yawning cools the brain down and prevents it from overheating, much like the fan in your computer. This might be why we are thirstier for sleeping and yawning in warm temperatures.

We yawn more when we’re tired and ready for a short sleep, and we can’t control when we do it! But it’s also true that yawning is a very contagious behavior. John Drury, a researcher, told BBC that, “It’s something that you can’t stop. Dogs yawn when their owners yawn, and animals yawn to each other. It happens whether you want to or not.”

His research into this behavior showed that there is a connection with our social group and how close we are to the people in it. If we are closely connected with the person who has the behavior, we are likely to copy it, too.

Another research showed similar results. They asked volunteers to watch other people yawn. They found that they hardly avoided yawning when others around them yawned. They also found, when using electrical stimulation (刺激), they were able to increase people’s wish to yawn. These findings could be useful because they could help treat other conditions like Tourette’s (图雷特氏综合症).

Every student knows the importance of taking notes in class. But taking notes is not actually that easy as it sounds.     16    

Begin with the note and the topic (主题).

    17     But this will help you keep your notes organized (有条理的). So it can be easy for you to review the notes.

    18    

Trying to write down everything the speaker says will only make you upset. Instead, listen for the key ideas the person wants to communicate. And you can write down the key words on your notebook.

Think about whether you want to take notes by hand or with a computer.

Writing notes by hand has been shown to help you remember things better.     19     Perhaps the best way is to write notes by hand first, and then type them up as part of your review.

Look over your notes again after taking them

    20     You’d better do this as soon as possible, so that you don’t forget anything. It will also increase the chances of remembering what you have written.