题干

A、B两种固体物质的溶解度曲线如图所示,据图回答下列问题:

(1)分别将相同质量的A、B饱和溶液,从30℃降到20℃,析出晶体较多的是 ____  (填“A”或“B”).

(2)30℃时,将20g物质A溶于50g水中,所得溶液中溶质的质量分数为____ .

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答案(点此获取答案解析)

A,27%

同类题2

阅读短文,根据短文内容回答问题。
    We've all heard of mermaids. They are the beautiful half-human, half-fish creatures(生物). They have the head and body of a human and the tail of a fish. We also know that mermaids only exist in fairy tales. But where did all the stories about these creatures come from? If you have ever seen a manatee, then you might have an idea.
    Manatees, which are also called sea cows, are mammals(哺乳动物) that live in the sea. Since they are mammals, they have to swim up to the surface to breathe air. Many people believe that the story of the mermaid began with the ancient sailors who saw the manatees putting their heads out of the water to breathe. Because manatees are upright when they do this, it looks like they are standing. If a sailor saw a manatee doing this from far away across the sea, it is possible that the sailor would mistake the manatee for a creature that is half-human, half-fish.
Mermaids are described as having very long hair. This is probably because manatees like to swim up to the surface of the water in areas where there is sea grass. Manatees eat all kinds of plants in the sea, including sea grass. The sea grass around the manatee’s head when they eat could create a picture of long hair.

    Manatees also have powerful tails that are very similar to the fish-like tail of a mermaid. The sailors probably watched manatees come up for air and then swim back below the surface, using their paddle-shaped tails. This would explain why the sailors thought mermaids had fish-like tails.

同类题3

      阅读下文,回答相关问题

      ①没有意识到错过,或许能产生一种自足感,但那意味着灵魂堕入了颟顸的渊薮。
      ②能意识到自己错过了什么,在追悔中产生出一种真切而细微、深入而丰厚的情愫,则意味着灵魂具备了升腾的能力。
      ③有的所错过的,还有机会再次相遇,正因为对错过有了痛切的感受,当机遇再次呈现时,你便会有高度的应变力与把握力,也许,那最后的结果,是与其在上次侥幸抓获,不如这回你冷静而成熟地驾驭……恰恰是因为你上次的错过,才导致了你这次的获得硕果!
      ④有的所错过的,时不复返,机不再来,属于永远的错过,但因为你善于细细咀嚼这错过的苦果,竟能从惆怅中升华出憬悟,乃至于酿出诗意与哲理……你的生命,或许反更有厚度;你的心灵,或许反更有虹彩。
      ⑤一念之差中,失之交臂了吗?有时我们虽然错过,只要我们立刻意识到了,并立刻追上前去,力挽狂澜于既倒,我们多半也还可以使错过转化为掌握;问题是我们往往在立即意识到了以后,竟滞涩、凝结住了我们的行动;这样的错过,则几近于过错。
      ⑥错过,即“有所失”,我们要习惯它。
      ⑦错过,也往往构成另一种得,我们要品味它。
      ⑧人生如奔驰的列车,车窗外不断闪动着变幻不定的景色,错过观览窗外的美景、奇景并不是多么不得了的事,关键是我们不能错过预定的到站。
      ⑨我们预定的到站并不等于人生的终点。但在人生的终点上,我们最好能含笑地说:我虽然错过的很多很多,却毕竟把握住了最关键最美好的,这样,“错过”便仿佛是碧绿的叶片,把一生中“收获”的七彩鲜花映衬得格外明艳!