题目

将CO2通入下列溶液中，不可能产生沉淀的是(    ) A.CaCl2溶液                                   B.Ca(OH)2溶液 C.Na2SO3溶液                                  D.Na2SiO3溶液 答案：AC 解析:A选项中，CaCl2是强酸盐，它不能和弱酸(CO2水溶液)发生反应；B选项中，Ca(OH)2是碱，它能和CO2(酸性氧化物)发生反应，生成CaCO3沉淀；C选项中，Na2SO3是强酸盐，它也不能和弱酸(CO2水溶液)发生反应；D选项中，由于硅酸的酸性比碳酸还弱，所以Na2SiO3溶液会与CO2发生下列反应：Na2SiO3+CO2+H2O====H2SiO3↓+Na2The other day I heard a few local musicians talking: “I hate all the terrible pianos in this town. I hate that rubbish they play on the radio. They can’t even understand a bit of music.” “I’m never playing in that club again. Too many drunks and nobody listens to us.” But, one younger musician said, “There are a few clubs that book my band a few nights a month, and I’m trying to find other places to play. I’m also looking to book a few summer festivals this year.” I’ve heard that you are the average of the five people whom you spend the most time with, or to put it another way, you are who your friends are. Attitudes are important. Whether they’re positive or negative, they’re rubbing off on you. If you’re around people who complain about lack of work and about other musicians, or blame others, and you play the role of victim, chances are you will start to as well. So it’s time to take a look at the people you call “friends”. This is an easy exercise: Make a list of the people who you hang out with, and simply stop spending time with the negative people on your list. Set a new standard for yourself and don’t become friends with people who fall below that standard.Keep successful people around you and your own chances for success will be much better. Ask them how they do it. Ask if they will help you get the work you’re looking for, or maybe give you some advice to help you on your career path.【1】Which of the following would be the best title for this passage?A. A friend in need is a friend indeedB. How to make friendship last for everC. You are who your friends areD. Friends are the most important in one’s success【2】The musicians’ words at the beginning are written mainly to show ________.A. the musicians’ living conditions are quite poorB. people have poor taste in musicC. people have different attitudes towards the same thingD. young people have greater chances of succeeding【3】By taking the exercise mentioned in Paragraph 7(underlined), you can ________.A. improve a lot in making more friendsB. come to the right way of making friendsC. develop a better relationship with your friendsD. arrange the time with your friends properly【4】The passage is mainly written for ________.A. musicians B. managersC. negative people D. people wanting to succeed