高压操作的效果是（）A、有利于提高产量 B、可以降低焦比 C、铁水中[Si]降低

网上银行信息安全规范可分为（）

A.安全使用规范

B.安全技术规范

C.安全管理规范

D.业务运作安全规范

如何从石油中获得更多的轻质燃油一直是化学家探索的课题,将石油分馏得到的重油进行裂化可以获得更多的轻质燃油。 

资料一:石蜡是含有20- 30个碳原子的烷烃的混合物,常温下呈固态。 

资料二:石油的催化裂化通常使用Al₂O₃做催化剂。某研究性学习小组在实验室中模拟石油的催化裂化。

装置如图:实验过程中可观察到烧杯Ⅰ中固体石蜡先熔化,试管Ⅱ中有少量液体凝结,试管Ⅲ中酸性高锰酸钾溶液褪色,实验后闻到试管Ⅱ中液体具有汽油的气味。

(1)该装置仪器连接的顺序应遵循的原则为_____________,为保证实验成功,实验前必须进行的操作是_____________,装置中较长导管的作用是_____________。 

(2)试管Ⅱ中少量液体凝结说明了__________________________。 

(3)试管Ⅲ中溶液褪色说明了__________________________。 

(4)能否用试管Ⅱ中的液体萃取溴水中的溴,理由是__________________________。 

(5)写出二十烷裂化得到癸烷和癸烯的化学方程式__________________________。 

(6)石油裂化的重要意义是__________________________。 

Learning Chinese has been like climbing a steep(陡峭的)mountain.

My mother was born in Tokyo,while my father moved from Shanghai to Hong Kong when he was seven years old. At home we speak English. I know some basic Chinese customs :to use chosticks gracefully (得体地)and what to say on Spring Festival to get a red envelope. But I never truly learned to speak Chinese.

Why should I need to learn the language ,anyway? I live in America where everyone speaks English.

I realized I was wrong in ninth grade when I arrived at Philips Academy,a famous boarding school in Massachusetts.The school encourages a global outlook(视野). There I decided to welcome the opportunity to learn Chinese. I met other American-born Chinese and together we spoke Ching-lish outside of the classroom.

I searched for ways to access Chinese culture through dramas such as Meteor Garden (《流星花园》)and music by singers such as S.H.E,Wilbur Pan and Jasmine Leung（梁静茹）. Listening to Chinese music is where I found my favorite singer in the whole world:Jay Chou. Even if I cannot understand what he is crooning（哼唱）, I do feel more Chinese whenever I listen to his music.

Last summer I spent five weeks in China,four of which were taking a language course at a Beijing high school. I was proud when I could understand the dialogue in Intitial D（《头文字D》） and when I could easily translate Fairy Tale sung by Kong Leung（光良）.

Learning Chinese has been a rocky trek（艰苦跋涉）, and I know it will continue to be that way before I arrive at a relative plateau（高地） of fluency（流利）.I hope that one day I will be able to work and maybe even live in China as a true Chinese.

1、The author wrote the text mainly to___.

A.share her experience of learning Chinese

B.tell us why she is interested in learning Chinese

C.show off(炫耀) the progress she made in learning Chinese

D.give advice on how to learn Chinese

2、The author's attitude to learning Chinese changed because___.

A.she found Chinese was interesting to learn

B.she wanted to take a course to pass easily

C.she realized she should have an open mind to the outside world

D.she made friends with some American___born Chinese at the school she studied

3、The author tried all of the following to learn Chinese EXCEPT___.

A.listening to Chinese music

B.practicing speaking Chinese with her parents

C.enjoying Chinese dramas

D.taking a Chinese course in China

4、We can learn from the text that___.

A.S.H.E.is the author's favorite singer

B.dialogues in Meteor Garden are easy to guess

C.the author enjoys learning Chinese though it is difficult

D.the author can speak fluent Chinese now

在OSSMO中，气候月报中的数据由A文件读取，并自动进行有关统计得到。

下列各选项中，不属于序言性注释的是( )。

A) 程序标题
B) 程序设计者
C) 主要算法
D) 数据状态