题干

下列根据实验操作和现象所得出的结论正确的是(   )
选项实验操作实验现象结论
A向鸡蛋清溶液中滴加饱和Na2SO4溶液有固体析出Na2SO4能使蛋白质发生变性
B向淀粉KI溶液中滴加氯水至过量溶液先变蓝后褪色I-先被氧化成I2,后可能继续被氧化成其他物质
C向浓度均为0.1 mol·L-1的NaCl和Na2SiO3溶液中分别滴加酚酞NaCl溶液不变色,Na2SiO3溶液变成红色非金属性:Si<Cl
D向浓度均为0.1 mol·L-1 NaCl和Na2CrO4混合溶液中滴加0.1 mol·L-1 AgNO3溶液先生成白色的AgCl沉淀Ksp(AgCl)<Ksp(Ag2CrO4)

A:A   

B:B   

C:C   

D:D

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答案(点此获取答案解析)

B

同类题2

Many people think sports are just for winning and honor, but there is a lot more you can gain from (get out of) them. I have learned over the past years that sometimes when I lose, I get a lot more out of it than winning. Also, I find a lot of times in sports, people are getting too caught up in the game instead of just having fun. The real purpose of sports is to have fun and learn life lessons along the way.
I greatly encourage you to be a part of the school sports. Even if you are not the best, you can still have fun. Sports give people a great and healthy way of spending an afternoon, instead of lying around playing video games or even getting into bad things. Sports also give us a sense of achievement. There isn’t a better feeling than to have done something fun and productive for my day.
I think that we all need sports to give us courage. If we try hard in sports, we usually do well. If we did the same in study, we would all be champions. Another reason why I encourage you to play sports is that it’s just fun. Without sports, our lives would just be boring. So as you may be able to tell, sports are amazing!
Our coaches not only teach us to play sports, but show class and good sportsmanship while playing them. It’s never fun when you lose to have the competitor rub it in your face. That’s why our coaches teach us to show class when we lose; also, when coaches get onto you, don’t get down. They only want to see you improve and learn from what they say. When you do badly and they don’t shout loudly is when you should start worrying because they are giving up on you.
Overall, sports are great! They bring out the best and worst of a lot of us. However, we can’ t let sports get too serious to where it brings down all the fun. So to have the most fun in sports, you just need try your best and not worry so much about the winning or losing.