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问题 选择题

如图为A、B、C三种固体的溶解度曲线，下列说法正确的是（　　）

A．在t1℃时，三种物质溶解度大小顺序为：A＞B＞C

B．在t2℃时，A、B饱和溶液的溶质质量分数相等

C．在温度大于t3℃、小于t4℃时，三种物质的溶解度大小顺序为：B＞A＞C

D．相同质量的三种物质的饱和溶液，温度由t4℃冷却至t1℃时，析出晶体（不含结晶水）的质量大小为A＞C＞B

答案

A、从t1℃向上做垂线，与曲线的交点在上面的溶解度就大，所以t1℃时它们的溶解度大小顺序是C＞B＞A，故A错；

B、饱和溶液的质量分数可以用该公式计算：

溶解度
100g+溶解度
×100%，所以饱和溶液的质量分数取决于溶解度的大小，t2℃时B的溶解度大于A的，所以B物质饱和溶液的溶质质量分数大于A物质饱和溶液的溶质质量分数，故B错；

C、在温度大于t3℃、小于t4℃时，溶解度在上面的，溶解度就大，所以三种物质的溶解度大小顺序为：B＞A＞C，故C正确；

D、温度由t4℃冷却至t1℃时，溶解度减小的多的析出晶体就多．由图示可知A物质的溶解度减小的最多，B物质次之，C物质减小的最少，所以析出晶体（不含结晶水）的质量大小为A＞B＞C，故D错．

故选C．

单项选择题

Never mind the obesity epidemic—Canada is (31) with an epidemic of bad ideas on how to fight obesity. The latest is to treat fast-food restaurants as if they were (32) to porn shops, and (33) them from—or at least limit their numbers in—neighbourhoods with schools or hospitals.
That idea is one of many (34) by a group of medical doctors in an article published this week in the Canadian Medical Association Journal. The doctors, (35) by the cardiologist Mark Eisenberg of McGill University, seem to view a bag of potato chips as the moral (36) of a package of cigarettes. They (37) propose the use of graphic warnings for junk food, similar to (38) on cigarette packages," which now have pictures of a dying cancer (39) on them. They would discuss a (40) on junk foods. Salt they suggest removing from processed foods not (41) , so that no one notices, but fast enough to destroy the enticing taste.
There is a logical end to this kind of thinking: men skulking on street corners (42) hamburgers under their trench coats, even as a massive bureaucracy decides how to separate junk foods from (43) ones, for the purposes of launching a fusillade of taxes. (The authors even envision a utopia in which people snack on "trail mix, apple slices and granola bars. ")
Canada does not need a dietitian-in-chief. It doesn’t need healthy-food enforcement officers. People in a democracy should be (44) to make bad choices, even ones as reprehensible as scarfing chips or swilling sugary pop. These choices are different from cigarette smoking, which creates (45) effects on others.

A. therefore B. nevertheless C. again D. even

A new report on children’s inactivity suffers from a similar flaw. Active Healthy Kids Canada complains that 72 percent of youth from the age of 5 to 19 do not have (46) to after-school programs. But why should 19-year-olds, or even the bulk of 14-year-olds, need such regimentation The attitude seems to be that only the government can (47) children from bad habits. How the state is supposed to program the pounds off today’s children is not explained.
Demonizing smoking is very different from demonizing obesity, (48) is a condition, not a behaviour. It is influenced by (49) factors. Shaming and blaming, taxing and banning, will not work. We need to promote greater (50) , at all ages, and all weights, and keep in mind that the heavy hand of the state is not the answer to every ill.
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单项选择题

理论与实践具有十分密切的关系，理论对实践具有指导的作用，有正确理论指导的实践会走向成功；错误理论指导的实践则一般都会失败。因此( )

A．实践都是有理论作为指导

B．应当坚持正确理论的指导

C．正确的理论指导正确的实践

D．错误的理论指导错误的实践
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