如图为固体物质X、Y的溶解度曲线。在温度为t2℃时分别把质量为a_爱下问搜题

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问题选择题

如图为固体物质X、Y的溶解度曲线。在温度为t₂℃时分别把质量为a g的X、Y放入100 g水中，下表为对溶液状态的判断以及使不饱和溶液达到饱和采取的措施。其中正确的是

	状态	措施
A	X为饱和溶液，Y为不饱和溶液	给Y溶液加热蒸发适量的水
B	X为不饱和溶液，Y为饱和溶液	向X溶液加入固体X至有晶体残留
C	X、Y都是饱和溶液。
D	X、Y都是不饱和溶液。	把X溶液温度降低至t₁℃，给Y溶液加热蒸发适量的水

答案

答案：B

分析：固体溶解度曲线上及上方的点表示的都是该固体物质的饱和溶液，而溶解度下方的点则表示的是该物质的不饱和溶液；根据固体物质的溶解度随温度变化的变化情况，可以判断出通过降温还是升温的方法使不饱和溶液变成饱和溶液．

解：A、由两物质的溶解度曲线可知，在t₂℃时，X的溶解度大于ag，而Y的溶解度小于ag，因此质量为a g的X、Y放入100g水中，X溶液是不饱和溶液，而Y溶液是饱和溶液，且溶液中还有未溶解的溶质；故A错误；

B、由于X溶液在t₂℃时是不饱和溶液，因此可以向溶液中添加溶质直至溶液达到饱和，故B正确；

C、由于X溶液是不饱和溶液，故C错误；

D、由于Y溶液是饱和溶液，故D错误；

故选B．

点评：本题难度不是很大，主要考查了根据溶解度曲线来判断溶液的状态，及根据溶解度曲线来判断采取什么样的方法使溶液由不饱和变成饱和溶液

完形填空

Most worthwhile careers require some kind of specialized training. Ideally, therefore, the choice
of an __36__ should be made even before choice of a curriculum in high school. Actually, __37__, most people make several job choices during their working lives, __38__ because of economic and industrial changes and partly to improve __39__ position. The "one perfect job" does not exist. Young people should __40__ enter into a broad flexible training program that will __41__ them for a field of work rather than for a single __42__ .
Unfortunately many young people have to make career plans __43__ benefit of help from a competent vocational counselor or psychologist. Knowing __44__ about the occupational world, or themselves for that matter, they choose their lifework on a hit-or-miss __45__. Some drift from job to job. Others __46__ to work in which they are unhappy and for which they are not fitted.
One common mistake is choosing an occupation for __47__ real or imagined prestige (声望).
Too many high-school students - or their parents for them - choose the professional field, __48__ both the relatively small percentage of workers in the professions and the extremely high educational and personal __49__. The imagined or real prestige of a profession or a White-collar job is __50__ good reason for choosing it as life’s work. __51__, these occupations are not always well paid. Since a large percentage of jobs are in mechanical and manual work, the __52__ of young people should give serious __53__ to these fields.
Before making an occupational choice, a person should have a general idea of what he wants __54__ life and how hard he is willing to work to get it. Some people desire social prestige, others intellectual satisfaction. Some want security; others are willing to take __55__ for financial gain. Each occupational choice has its demands as well as its rewards.

A．identification

B．accommodation

D．entertainment

C．furthermore

D．opportunity

D．considering

A．preferences

B．requirements

C．Nevertheless

D．consideration

单项选择题

在订票类型中，车站订票分为社会订票和（）。

A.团体订票

B.合同订票

C.学校订票

D.旅游订票