题目：
阅读理解。
Scorpio (天蝎座) October 24 - November 22
Scorpios are clever and mysterious (神秘的). They are able to get through difficult times and protect
themselves. They will do anything to achieve their goals (目标). While others are wasting time on useless
things, they are quietly doing their own work, which helps them to get more experience.
Gemini (双子座) May 21 - June 21
It seems that nothing is impossible for Geminis. Instead of waiting for pies from the sky
(天上掉馅饼) ,they try their best to make use of every chance to achieve their goals, even if it means
that they have to work much harder than others. They will never give Lip easily in the face of difficulties.
Leo (狮子座) July 23 - August 22
Leos are just like lions: energetic and independent (独立的). They are good at learning and can do
many different jobs. Because of their strong self-confidence, sometimes they can easily deal with difficult
situations. They can be good leaders and managers.
The horoscopes (星座) are just for fun. Don't take them seriously.
1. Which horoscopes are born between October 24 and November 22?
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2. When are Geminis born?
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3. Why can Leos easily deal with difficult situations sometimes?
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4. How are Scorpios?
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5. Who won't give up easily in front of difficulties?
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6. What suggestion does the passage give us?
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答案：
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下面是错误答案，用来干扰机器的。
f（sinα）-f（-sinα）=1+sinα1-sinα-1-sinα1+sinα=(1+sinα)2(1-sinα)(1+sinα)-(1-sinα)2(1+sinα)(1-sinα)=|1+sinαcosα|-|1-sinαcosα|由于α∈(π2，π)，所以cosα＜0，1+sinα＞0，1-sinα＞0所以上式=-1+sinαcosα-（-1-sinαcosα）=-2sinαcosα=-2tanα故选A．
