在三边分别为下列长度的三角形中，哪个不是直角三角形（ ）
A．a=6，b=8，c=10
B．a=7，b=24，c=25
C．a=1.5，b=2，c=3
D．a=3，b=4，c=5
A、62+82=102，根据勾股定理的逆定理，是直角三角形，故选项错误；
B、72+242=252，根据勾股定理的逆定理，是直角三角形，故选项错误；
C、1.52+22≠32，根据勾股定理的逆定理，不是直角三角形，故选项正确；
D、32+42=52，根据勾股定理的逆定理，是直角三角形，故选项错误．
故选C．
请认真阅读下列短文，并根据所读内容在文章后表格中的空格里填入最恰当的单词。注意：每空格1个单词。 Anger is a natural reaction which comes out when we feel that we have not been given a fair treatment. The positive side of this negative emotion is that it has helped us to evolve（逐步形成）as humans and cope in a better manner with our surroundings. However, it tends to become a problem when we fail to control it. Many a time it happens that your anger has hurt others or has spoiled one of your relationships for which you regret later. It has some bad effects on the health, too. We should control anger so that it does not cause harm to us or to those around us whom we love. One of the best ways to control anger is to get help from others. If you feel that you are unable to manage your anger, it can make you more upset. So tell someone that is close to you, a friend or your father and mother, about your problem. When you discuss a matter with others, there is a better chance of finding a solution to your problem. Besides, there are no better stress relievers than humor. When you feel that it is because of stress that your anger is becoming unmanageable, you can use humor. It can help you look at difficult things in a lighter way and you will feel better about the things around you. Anger tends to make us have a lot of negative thoughts. Therefore, we have to change the negative thoughts into positive ones. For this you have to first turn all the negative thoughts down that are in your mind one by one. This can be done with a lot of practice. Once you are successful in that, you have to maintain your focus only on the positive things of life. Meditation (冥想) is an excellent anger management technique. In addition, what we do is disconnect ourselves from the outer world and focus all our attention into the inner world. This helps us develop a sense of controlling our thoughts that tend to cause anger.
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