问题 单项选择题

Chomd744test命令执行的结果是()

A、test文件的所有者具有执行读写权限,文件所属的组和其他用户有读的权限

B、test文件的所有者具有执行读写和执行权限,文件所属的组和其他用户有读的权限

C、test文件的所有者具有执行读和执行权限,文件所属的组和其他用户有读的权限

D、test文件的所有者具有执行读写和执行权限,文件所属的组和其他用户有读和写的权限

答案

参考答案:B

填空题

为了探究影响固体溶解性的因素,某同学设计了如下三组实验

因素第一组第二组第三组
实验温度20℃20℃20℃20℃80℃
加入溶剂种类酒精
加入溶剂质量20g20g10g10g10g
加入固体种类硝酸钾硝酸钾硝酸钾食盐硝酸钾
加入固体质量10g10g10g10g10g
溶解固体质量6.2g0g3.1g3.6g10g
(1)分析上表,第一组实验研究的因素是______;

(2)由上述实验可知,影响固体溶解性的因素是(填序号)______;

①温度 ②加入溶剂种类 ③加入溶剂质量 ④加入固体种类 ⑤加入固体质量

(3)在第二组实验中,该同学按照如下步骤进行实验(假设溶液损失不计)

1、用电子天平称取10.0g硝酸钾,放入烧杯中;

2、量取10.0mL水,倒入上述烧杯中,称量烧杯、硝酸钾和水的总质量为m1g;

3、搅拌至硝酸钾不再溶解为止;

4、过滤,称量所得硝酸钾溶液和烧杯的总质量为m2g;

5、计算:m1-m2=______g(结合第二组实验数据进行分析).

将溶质改为食盐,重复上述步骤进行实验.

由实验可知,20℃时食盐的溶解性______(填“>”“﹦”“<”)硝酸钾的溶解性.

(4)根据上述实验,以下推论正确的是______

A.20℃时,氯化钠的溶解度为36g/100g水

B.20℃时,硝酸钾饱和溶液的溶质质量分数为31%

C.第三组实验中的硝酸钾溶液为80℃时的饱和溶液

D.20℃的任意一杯饱和硝酸钾溶液中,溶质与溶剂的质量比一定相等.

阅读理解

阅读理解。

     During my high school years, the most important thing was what I was wearing to the Friday night dance

and who I was taking. Although college was talked about, it was the least of my worries. When I was

graduating eighth grade and starting high school, my older brother was graduating twelfth grade and going

onto college. For my graduation, he gave me a card in which he wrote,"Enjoy your four years... they go by

fast." I remember not believing him then, but looking back... he was right. Those four years shaped who I

was as a person, pushed me to my limit and encouraged me to become an adult.

      However, I was so completely absorbed in my junior and senior years of high school, that when someone

spoke of college I brushed it off. I wasn't ready to leave my comfort zone of having all of my closest friends

together and knowing what every single day was going to be like. Studying was something I did only AFTER

 I nailed my half-time dance performance. I knew my parents wanted me to go to college, so I told them I

would go to community college (社区学院) and I didn't worry about my SAT (美国大学入学考试) scores.

      When my senior year passed and everyone graduated and went off to their own colleges, I started to wish

I had done the same. My friends were living away, meeting new people, discovering new places, and I was

living at home and driving to and from class every day. It seemed exactly like high school. I hated it! I thought

college was supposed to be different! Why didn't I take more time to research colleges and do the same? I

ended up loving college and wishing I had four years to enjoy the campus (大学校园) atmosphere instead of

two.

     My advice to anyone thinking about attending college is to think about it very seriously and look into all of

your choices well ahead of time. Now I have graduated and I am working full time and I would do anything to

go back to my high school days for a second chance!

1. Why didn't the author worry about his SAT scores?

A. He wanted to go to community college.

B. He had been admitted for his gift in dance.

C. He was well prepared for the exam

D. He believed his brother would help him

2. When in high school, the author _____.

A. drove to and from class every day

B. buried himself in his study all the time

C. enjoyed talking about future college life

D. lived in the school except on holidays

3. what did the author's brother mean by "Enjoy your four years... they go by Fast"?

A. He wished the author to have more dance.

B. He advised the author to value the years.

C. He encouraged the author to leave his comfort zone.

D. He suggested the author aim at a community college.

4. Talking of his high school years, the author feels  _____.

A. regretful

B. lonely

C. angry

D. pleased