题干

下表为氯化铵和氯化钠在不同温度时的溶解度。下列说法正确的是(  )

温度/℃

0

10

20

30

40

50

NH4Cl

溶解度/g

29.4

33.3

37.2

41.4

45.8

50.4

NaCl

溶解度/g

35.7

35.8

36.0

36.3

36.6

37.0

A:20 ℃,氯化钠饱和溶液的溶质质量分数为36%

B:由表中数据可知,溶解度受温度变化影响较大的物质是氯化钠

C:氯化钠与氯化铵溶解度相等的温度在10 ℃~20 ℃之间

D:50 ℃时,100 g水中加入50.0 g氯化铵配成溶液,再冷却到20 ℃,能够析出13.2 g固体

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答案(点此获取答案解析)

C

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完形填空。

    It was the end of the week at the village school. The bell had rung, and the children had run out into the bright sunshine, wild with laughter and fun. All were happy but poor Davy. He came out last and very1. He was in trouble, and the bright, golden sunlight did not make him2. He walked across the yard, and sat down on a stone behind the old maple. A little bird on the highest branch sang just to make him3. But Davy did not notice it. He was thinking of the4words that had been said about his ragged clothes. The5stole out of his eyes, and ran down his cheeks. Poor little Davy had no6, and his mother had to work hard to keep him at school all by herself. He did not wish to trouble his mother; so he 7among the trees , and at last threw himself on the green moss under them. Just then his beloved teacher Mrs. Smith came8. She saw who it was, smith stopped to ask what was the9 . Davy did not speak, but the tears began to start. Mrs. Smith waited patiently10Davy told her all his  trouble. When he ended, she said11, “Davy. I have a plan which I think will help you.” “Oh , what is it ?” He said, sitting up with a look of 12while a tear fell upon a blue violet. “Well, how would you like to be a little flower13? And earn money?” “That would be jolly. But where shall I get my flowers?” he asked. “14, my boy, the answer to the question is just right in there15.” said Mrs. Smith. “Here are lively blue violets, down by the brook are white ones, and among the rocks are ferns and mosses. 16them all to my house, and I will help you17them.” Davy nodded and went home happily. Day after day. Davy hunted the woods for the18flowers, and the most beautiful ferns and mosses. After his teacher had helped him with new clothes. But for the19, and sold them. He soon carted enough money to buy new clothes. But for the20of his teacher, he couldn't have solved his problem. Now he could see the bright sunshine and hear the bird's singing.

同类题5

     阅读,回答文后问题
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      ②因为花费时间太多,我选择每周刮一次胡子,即在每个星期天的早上。我不留大胡子,因为如果在突发事件中需要戴上防毒面具,胡子可能会阻碍全脸面具的密封。一周刮一次胡子变成了一种计时的方法。如果我在镜子里瞥见一张脏乱的脸孔,我就知道是星期五或者星期六,我又熬过了一周。
      ③我的床是光谱太空舱后面的一堵墙,对面的地板上有一台通气扇。因为在太空中热空气不会上升,这里没有空气对流,风扇是使空气流动的惟一途径。
      ④睡在一个不够通风的地方,你很可能会像是在一个氧气不足与二氧化碳过剩的罩子里呼吸。结果会导致缺氧与换气过度。人醒过来时会感到剧烈的头疼,且会拼命吸气。
      ⑤出于这个原因,我头脚倒置睡在墙上,头冲着那台运行的风扇,我用一根BUNGEE绳或是一条尼龙褡裢防止自己在夜里漂走。我见过其他宇航员在睡觉时到处漂浮——他们在晚上绕着飞船漂浮,通常撞上过滤器的吸入一侧时才会醒来。
      ⑥就这样我在太空中生活了五个月。尽管不太方便,我并不因为缺少愉快事物而厌烦。记得我还是小男孩的时候,晚上洗澡常常呻吟抱怨,在这种意义上,我认为空间站是小孩子的天堂。另外,蓬乱,不刮胡子,甚至有点乱糟糟的,似乎很适合太空探险的景象。我们毕竟是在前线的冒险者,忙得根本无暇顾及自己看上去怎样或者闻起来怎样。