题目

现有以下反应①Cl2+2KBr═2KCl+Br2，②KClO3+6HCl═3Cl2+KCl+3H2O，③2KBrO3+Cl2═Br2+2KClO3，下列说法正确的是．( )A.上述三个反应都有单质生成，所以都是置换反应B.氧化性由强到弱顺序为 KBrO3>KClO3>Cl2>Br2C.反应②中还原剂与氧化剂的物质的量之比为6：1D.③中lmol还原剂反应则氧化剂得到电子的物质的量为2mol 答案：【答案】B【解析】A．置换反应中不仅有单质生成还必须有单质参加，②中生成物有单质但反应物没有单质，所以不是置换反应，故A错误； B．①Cl2+2KBr=2KCl+Br2中氧化剂是氯气，氧化产物是溴，所以氯气的氧化性大于溴，②KClO3+6HCl=3Cl2+KCl+3H2O中氧化剂是氯酸钾，氧化产物是氯气，氯酸钾的氧化性大于氯气Stress is everywhere in our everyday life. Not only men have it, but also women and young people.The most important reasons of stress are: death, diseases, exams, making money, getting married, moving houses, changing jobs, ending friendships and so on.How do you know whether you have stress or not? Could you give your answers to the following questions?Stress TestDo you...YesNoEasily get angry?  Often sleep badly?  Get headaches a lot?  Take medicine to help sleep?  Find it difficult to relax?  Usually hide your feeling?  Smoke and drink a lot to keep quiet?  Find it difficult to put your heart into something?  If your answer "Yes" to more than two of these questions, you are one of those people with stress. So what can you do about it?Doing relaxing exercises, talking with friends and listening to light music are all usual ways of relieving (减轻) stress. However, doctors now say that there are easier ways-people should laugh and smile more often. When you laugh and smile, your body relaxes. They also say that people, especially men, should   X  more often, because crying is a natural way of relieving stress.小题1:Which of the following is NOT the reason of the stress?A．Taking exams.B．Changing jobs.C．Taking medicine to help sleep.D．Making money.小题2:According to the passage, which of the following is true?A．Women and young people never have stress.B．Stress is everywhere in our everyday life.C．People who answer "No" to all of the questions have great stress.D．People who answer "Yes "to more than two of the questions have no stress.小题3:"X" in the passage should be the word "     ".A．cryB．laughC．smileD．smoke小题4:The main idea of the passage is      .A．about stress and how to relieve your stressB．that there are many reasons for having stress.C．that laughing and smiling more can help relieve your stress.D．that doing the Stress Test is a good way to help you live a better life.