下列不具有抗龋作用的矿物质或元素是（） A.氟 B.磷酸盐 C.铜 D.镁 E.铁

梁启超说：“我国蚩蚩四亿之众， 数千年受治于民贼政体之下，如盲鱼生长黑壑，不知天地间有二字。”省略的两字最可能是 [ ]

A．君主   

B．民权

C．西学  

D．科学

内外半径分别为R₁和R₂的同轴电缆，中间填充介电系数为ε的介质，介质允许的最大电场强度为E_max（又称介质的击穿场强），该电缆所能承受的最大电压为（）。

A．A

B．B

C．C

D．D

     I credit my typing skill to so many hours of chatting online. Unfortunately, as my typing speed

increased on the Internet, all grammatical rules went out of the window. You see instant messages

have their own shorthand language and grammar isn't important, of which even a newbie (新手) is

aware. They can leave out articles, subjects (主语), pronouns, etc. They can misspell or "respell"

almost any word. They often ask "A/S/L" when they first chat. Abbreviations (缩写) and

capitalizations (大写) are particularly important. English-speaking instant messengers also refuse

to burden themselves with punctuation and capitalization.

    After I came back China, I discovered not one but two instant messaging crazes. The first, which

brought back memories of my previous addiction to the computer, was QQ. I can see evidence that

the Chinese have the same kind of separate instant messaging language, even when they chat in

English. My first word in this language, for example, was "ft". This abbreviation for "faint" is used

whenever there is a need to express surprise. I also discovered that Chinese use the same kind of

abbreviation for a laugh. And there is an extraordinary number of smileys (表情符) to the "vomit"

and "army soldier" smileys. There is even a SARA smiley.

     After QQ, there is another, perhaps more widespread messaging trend. You guessed it-cell phone

text messaging. I now understand how useful text messaging is and why it is so common. I admit that

I have been guilty of sending text messages while walking outside or sitting on the subway. Who

hasn't ? No matter where I go, I see people on their cell phones, messaging. In fact, it's rare to see

someone actually talking on their phone!

     So it looks as if there is no escape from the instant messaging crazes, no matter where in the

world I go. And that's plainly not going to change. In the end, though, I can't complain: instant

messaging is quick, it's cheap, it's easy and it's extremely fun too. And after all, everyone's doing it.

1. The underlined phrase "went out of the window" in Paragraph 1 probably means        . 

A. increased  

B. occurred  

C. disappeared  

D. changed

2. Which of the following is true according to the passage?

A. Grammar and correct spelling are very important while chatting online. 

B. There are enough smileys and icons to express yourselves while chatting on line.

C. The writer is skilled at typing and once was addicted to online games.

D. It is impolite to leave out some unimportant words or letters while chatting online.

3. The writer believes that instant messaging is          .

A. full of fun but time-consuming  

B. widespread but unnecessary

C. quick but difficult to do  

D. common, used and cheap

4. Which might be the main idea of the passage?

A. Who can escape QQ and cell phone text messaging?  

B. Why is instant messaging so popular?

C. Chatting online is good for your typing skill.

D. Chatting on QQ is natural for people.    

添纱组织

下列（）属于建筑结构应满足的结构功能要求。

A.安全性

B.适用性

C.美观性

D.耐火性

E.耐久性