研究大气中含硫化合物（主要是SO₂和H₂S）的转化具有重要意义．

蔗糖颗粒加入水中最终形成无色溶液，这一现象不能说明（　　）

计算：3($\sqrt{3}$－π)⁰－$\frac{\sqrt{20}-\sqrt{15}}{\sqrt{5}}$＋(－1)^{2 013}.

完型填空

Jerry is the kind of guy you love to work and live with. He is always happy and always has something 1  to say. When someone asks him how he is doing, he must reply, “If I   2 any better, I would be twins! ”

Jerry is an 3 manager because he has several waiters who have followed him around from restaurant to restaurant. The reason the waiters follow him is his 4 to life. He always  5 others. If a waiter is having a bad day, Jerry is there telling the waiter how to  6the positive side of the situation.

I was very curious(好奇的) about his positive attitude, 7one day I went up to Jerry and asked him, “I don’t get it! You are a positive person 8. How do you do it? ”

Jerry replied, “Each morning I 9  and say to myself, ‘Jerry, you have two choices(选择) today. You can choose to be happy or you can choose to be unhappy. ’I choose to be happy. Each time something bad happens, I can choose to be a victim (牺牲品)or I can choose to learn from it. I choose to learn from it. ”

Life is all about choices. Please remember: “You are what you  10  . ”