下面关于RS-232标准的叙述中，错误的是( )。A．PC机串行接口的电气规范与R

某企业在投资初创期拟投资500万元，现有两个备选方案，资料见下表：

要求：计算两个方案的加权平均资本成本，并比较方案的优劣。

冰冻后的牛奶，热牛奶，酸牛奶与鲜牛奶相比，哪一个的营养成分更容易被人体吸收（）

A.鲜牛奶

B.冰冻后的牛奶

C.酸牛奶

D.热牛奶

患者，男性，78岁，进不洁食物后呕吐、腹泻3天，昏迷1天。既往有高血压病史10年。查体：T38.5℃P112次／分R26次／分BP70/50mmHg，压眶无反应。皮肤干燥，弹性极差，心、肺、腹无明显异常。尿糖（++++），酮体（±），临床诊断为高渗性非酮症糖尿病昏迷。

该病人更容易出现的异常项为以下（）

A.ALT、AST

B.BUN、Cr

C.ESR

D.血脂

E.TBIL

发动机机油黏度随（）而变化。

阅读理解。

     Imagine a classroom missing the one thing that's long been considered a necessary part to

reading and writing paper.No notebooks,no textbooks,no test paper.Nor are there any pencils

or pens,which always seem to run out of ink at the critical moment.A"paperless classroom"is

what more and more schools are trying to achieve.

     Students don't do any handwriting in this class.Instead,they use palm size,or

specially-designed computers.The teacher downloads texts from Internet libraries and sends

them to every student's personal computer.

     Having computers also means that students can use the Web.They can look up information

on any subject they're studying from maths to social science.

     High school teacher Judy Herrell in Florida,US,described how her class used the Web to

learn about the war in Afganistan(阿富汗) over one year ago.

     "We could touch every side of the country through different sites from the forest to refugee

camps(难民营),"she said."Using a book that's three or four years old is impossible."

     And exams can go online too.At a high school in Tennessee,US,students take tests on

their own computers.The teacher records the grades on the network for everyone to see and

then copies them to his own electronic grade book.

     A paperless classroom is a big step towards reducing the waste of paper.High school

teacher Stephanie Sorrell in Kentucky US said she used to give about 900 pieces of paper

each week to each student.

     "Think about the money and trees we could save with the computers,"she said.But,with

all this technology,there's always the risk that the machines will break_down.So, in case of

a power failure or technical problems, paper textbooks are still widely available(可用的) for

these hitech students.

1．What does the part of the last but one sentence in the first paragraph,"run out of ink at

the critical moment" mean?

A．Pens may not write welt at the critical moment.

B．Pens get lost easily,so you may not find them at the critical moment.

C．Pens may have little or no ink at the critical moment.

D．Pens use ink,while pencils don't.

2．In a paperless classroom, what is a must?

A．Pens.           

B．Computers.  

C．Information.               

D．Texts.

3．The high school teacher，Judy Herrell，used the example of her class to show that________.

A．the Web could take them everywhere

B．the Web taught them a lot

C．the Web is a good tool for information

D．the Web，better than the textbooks，can give the latest and comprehensive(全面的) information

4．The paperless classrooms will benefit ________ the most.

A．students          

B．teachers  

C．trees              

D．computers

5．What does the phrase in the last paragraph，“break down”，mean?

A．Break into pieces.        

B．Stop working.

C．Fall down.              

D．Lose control.