We use accounts receivable turnover in days to indicate the quality of the receivables turnover.

Why does the teacher say thisΩ?

A．To indicate that the university is very strict with students.

B．To suggest that the student should attend the lectures.

C．To encourage the student to do his part-time job.

D．To indicate that she is not concerned about the student's attendance.

The risk that is specific to individual stocks is called______.

A．systematic risk

B．unsystematic risk

C．country risk

D．market risk

The development of toothpaste began as long ago as 3000/5000 BC in the ancient countries of China and India. According to Chinese history, Huang-Ti claimed different types of pain felt in the mouth could be cured by sticking gold and silver needles into different parts of the jaw and gum. h was theories such as these that led to the development of dental cream. During the years 3000/5000 BC, Egyptians made toothpaste using a recipe of powdered ashes of hooves of oxen, myrrh, powdered and burned eggshells and pumice. It is assumed that the ancient Egyptians used their fingers to rub the mixture onto teeth.

The tooth stick, the forerunner of the toothbrush, had not, as far as is known, been discovered at this time. From the records of the ancient countries of India, China and Egypt, it was the Greeks and Romans who developed and improved toothpaste and developed a leaden instrument for the extraction of teeth. They were also the first to bind loose teeth together and to support artificial teeth by means of gold wire. During 1000 AD, the Persians gave advice on the dangers of using hard toothpowders and recommendations were made to make toothpowder from burnt hartshorn, the burnt shells of snails and oysters and burned gypsum. Other Persian recipes included dried animal parts, herbs, honey and minerals. One formula for strengthening teeth included green lead, verdigris, incense, honey and powdered flint stone.

Toothpowder or dentifrice was first available in Britain in the late 18th century. It came in a ceramic pot and was available either as a powder or paste. The rich applied it with brushes and the poor with their fingers. The powders were developed by doctors, dentists and chemists and often contained ingredients that were highly abrasive and harmful to the teeth, such as brick dust, china, earthenware or cuttlefish, and to make them more palatable, they contained glycerine. By the early nineteenth century, the ingredient stronchium was introduced, to strengthen teeth and reduce sensitivity, but it only really concentrated on the gums. In the late 18th century, borax powder was used to get the foaming effect. In 1873, an aromatic toothpaste in a jar was introduced in the U.S. and in 1896, Dental Cream was first packaged in collapsible tubes. Before the Second World War, the majority of toothpaste on the market used soap as an emulsifying agent, even though it was known that soap had certain inherent defects.

What is the main subject of the passage?

A．Methods of cleaning teeth.

B．Methods of caring for teeth.

C．Development of toothpaste.

D．Dental history.

A System of Guaranteed Subsistence Minimum

A hundred years ago it was assumed and scientifically "proved" by economists that the laws of society made it necessary to have a vast army of poor and jobless people in order to keep the economy going. To day, hardly anybody would dare to voice this principle. It is generally accepted that nobody should be excluded from the wealth of the nation, either by the laws of nature or by those of society. The opinions, which were current a hundred years ago, that the poor owed their conditions to their ignorance, lack of responsibility, are outdated. In all Western industrialized countries, a system of insurance has been introduced which guarantees everyone a minimum of subsistence in case of unemployment, sickness and old age. I would go one step further and argue that, even if these conditions are not present, everyone has the right to receive the means to subsist, in other words, he can claim this subsistence minimum without having to have any "reason". I would suggest, however, that it should be limited to a definite period of time, let's say two years, so as to avoid the encouraging of an abnormal attitude, which refuses any kind of social obligation.

This may sound like a fantastic proposal, but so, I think, our insurance system would have sounded to people a hundred years ago. The main objection to such a scheme would be that if each person were entitled to receive minimum support, people would not work. This assumption rests on the fallacy of the inherent laziness in human nature, actually, aside from abnormally lazy people, there would be very few who would not want to earn more than the minimum, and who would prefer to do nothing rather than work.

However, the suspicions against a system of guaranteed subsistence minimum are not groundless from the standpoint of those who want to use ownership of capital for the purpose of forcing others to accept the work conditions they offer. If nobody were forced to accept work in order not to starve, work would have to be sufficiently interesting and attractive to induce one to accept it. Freedom of contract is possible only if both parties are free to accept and reject it; in the present capitalist system this is not the case.

But such a system would not only be the beginning of real freedom of contract between employers and employees, its principal advantage would be the improvement of freedom in interpersonal relationships in every sphere of daily life.

People used to think that poverty and unemployment were due to ______.

A．the slow development of the economy

B．the fault of the poor and the jobless themselves

C．the lack of responsibility on the part of society

D．the large number of uneducated people

PURPOSE OF ACCOUNTING Every company has an accounting office or a finance department that looks ()its accounting details. An accounting department is the backbone(脊梁)of every business. It records all the business transactions(交易), and keeps a track(记录) of the incomes(收入) and expenses(支出)of the business. The accounting department also helps to determine the correct financial position and standing of the business. For a systematic(系统的)and ()recording of transactions, accounting is important. The purpose of accounting is recording all the transactions honestly and accurately in the “Books of Accounts(账本)”. The accounting process can be defined ()“the process that begins when the transaction takes place and ends ()the transaction is recorded in the books of accounts”. It includes a series of steps that ()to analyze(分析)and record the business transactions for a particular period.

1.A. forB. afterC. up

2.A. accurateB. simpleC. correct

3.A. toB. atC. as

4.A. whenB. whichC. what

5.A. useB. is usedC. uses

The thieves ______ the possibility of the alarm system sounding

A．overtook

B．overcame

C．overlooked

D．overworked

Computer Viruses

  

计算机病毒

  

Introduction

  A computer virus is a piece of software programmed to perform one major task: to replicate. Viruses accomplish their reproductive task by preying on other computer files, requiring a host program^[1]as a means of survival. Viruses gain control over their host in various ways, for example by attaching their infected code to the end of a host program and misguiding the header information at the beginning of the file so that it points toward itself rather than the legitimate program. Therefore, when an infected host program is run, the virus gets executed before the host. The host program can be almost anything: an application, part of the operating system's, part of the system boot code, or a device driver. The virus continues to spread, moving from file to file in this infectious manner.

  In addition to its propagation mission, many viruses contain code whose purpose is to cause damage. In some viruses, this code is activated by a trigger mechanism.^[2]A trigger condition may be linked to the number of times the host file is run, or it could be a response to a particular date, time or random number. In other cases, the damage could occur continuously or on a random basis. Of the 11,000 known viruses present today, more than 2,000 have been diagnosed as being data destructive.

  

Types of Viruses

  Several types of viruses exist and are classified according to their propagation patterns.

  1. Executable File Infectors

  These viruses spread infection by attaching to an executable file, misdirecting the header information, and executing before the host file. It is very common for these viruses to load themselves into memory once their infected host file is launched. From there, they monitor access calls, infecting programs as executed.

  2. Boot Sector Infectors

  This type of virus overwrites the original boot sector, replacing this portion of code with itself, so it is the first to load and gain control upon system boot, even before DOS. In order for boot block viruses to replicate, it is usually necessary to boot the computer from an infected floppy disk. Upon system boot, the virus will jump from the infected floppy disk to the hard disks partition table.

  3. Partition Table Infectors

  These viruses attack the hard disk partition table by moving it to a different sector and replacing the original partition table with its own infectious code. These viruses will then spread from the partition table to the boot sector of floppy disks as floppies are accessed. 4. Memory Resident Infectors

  Many viruses load themselves into memory while altering vital system services. For example, some viruses modify the operating system's Execute Program service in such a way that any executed program is immediately infected. Other viruses modify the operating system in order to camouflage their existence. These viruses are called Stealth Viruses.

  

Why Are Viruses Written?

  Bulgaria is often referred to as the "Virus Factory" because the country accounts for the highest percentage of new virus creation. Several cultural factors attribute to this state. Primarily, the country offers no software copyright protection, so legitimate software programmers are not rewarded financially for their work. And there are no laws in place to prohibit the authorship of new viruses. In fact, virus source code is often posted on international bulletin boards for anyone to access. Certainly, this is not the case in the United States, so why do we maintain the second highest level of virus authorship? Today's viruses are being written to attack a specific person, company or program. There are countless stories of disgruntled employees who seek vengeance by writing viruses to attack their former employer's computer system.

  

How Are Viruses Transmitted?

  Because a virus is nothing more than a piece of software, it can be acquired in the same way as legitimate programs. Viruses have reportedly been transmitted through shrink- wrapped retail software.^[3]Unsuspecting sales representatives often act as carriers by demonstrating infected programs. Newly purchased computers, which had their hard disks formatted by service technicians, have been returned with viruses. These pests travel over phone lines through programs sent by modem. Bulletin boards do occasionally transmit viruses. The most common means of contracting a virus, however, is through the use ot floppy disks. Piracy of software, in particular, expedites viral spread, as do floppy disks traveling from one computer to another.

  

We Are All at Risk

  All personal computer users are at risk for viral infection. Several events, trends and technological inroads have combined in the past few years to increase our vulnerability to infection. The proliferation of local area networks, the downloading of information from mainframes to desktop computers, our increased reliance on personal computers to store mission critical data, the arrival of electronic bulletin boards, the globalization of communications, the gained popularity of shareware, the growing use of remote communications, the increased sophistication of end users, the portability of data, the casual spread of software via piracy, and the staggering rate of new virus creation all contribute to increase our risk of virus infection.

  

A Special Threat to Networks

  Viruses present a special threat to networks because of the inherent connectivity they provide and because of the potential for widespread data loss. Once a virus infects a single networked computer, the average time required for it to infect another workstation is anywhere from 10 to 20 minutes. With a propagation time of this magnitude, a virus can paralyze an entire network in several hours.

  

Virus Infection Symptoms

  The most successful virus has no symptoms at all. Your computer may be infected, and you will notice no change in the normal behavior of your computer. The only way to be aware of such viruses is to use automated virus detection tools. Some less sophisticated viruses may exhibit "visible" symptoms such as:

  1) Changes in program length

  2) Changes in the data or time stamp

  3) Longer program load times

  4) Slower system operation

  5) Unexplained disk activities

  6) Unexplained reduction in memory or disk space

  7) Bad sectors on your floppy

  8) Disappearing programs

  9) Unusual error messages

  10) Unusual screen activity

  11) Access lights turn on for non-referenced drive

  12) Failed program execution

  It is important to remember that some viruses may not exhibit any visible symptoms at all. Don't count on your intuition as your only tool for detecting viruses.

  

Anti-Virus Tools

  In dealing with today's sophisticated viruses, intuition and strict employee policies are not enough. The more carefully engineered virus programs exhibit no visible symptoms at all until it is too late. Your computer may be infected with a virus without any noticeable alteration in functionality. Therefore, relying solely on visible side effects, such as slower system operation, longer program load time or unusual screen activity as a means of early detection, may not prove as reliable as it once did. You can no longer afford to count on your intuition as your only tool for detecting viruses. While information systems managers should establish employee guidelines and policies to lessen the potential for infection, strict rules alone will not insure complete protection. What about the shrink-wrapped software program purchased by your company that was later found to be infected by a virus? Or what about the hard drive that was sent out for repair by a service technician, only to^[4]have it returned with a virus? The only way to prevent viruses from mysteriously entering your company is to reinforce the security programs already in place with automated virus detection tools.

  

Defending against Viruses

  Following are some tips in helping to combat the growing threat of viral infection.

  1) Use an automated virus detection tool, such as Fifth Generation Systems Untouchable virus protection software.

  2) Regularly perform a backup of your data with a backup program, such as Fifth Generation Systems Fastback Plus.^[5]

  3) Prevent unauthorized access to your computer by using a security access program, such as Fifth Generation Systems Disklock.^[6]

  4) Use write-protected tabs on all program disks before installing any new software. If the software does not allow this, install it first, then apply the write-protected tabs.

  5) Do not install new software unless you know it has come from a reliable source. For instance, service technicians and sales representatives are common carriers of viruses. Scan all demonstration or repair software before use.

  6) Scan every floppy disk before use and check all files downloaded from a bulletin board or acquired from a modem.

  7) Educate employees. As the adage goes, an ounce of prevention is worth a pound of cure.

  8) Do not boot from any floppy disk^[7], other than a clean, DOS based disk.

  9) Avoid sharing software and machines.

  10) Store executable and other vital system parameters on a bootable DOS based disk and regularly compare this information to the current state of your hard drive.

  Notes

  [1]requiring a host program：host表示“主人”、“东道主”。此处a host program可译成“主机程序”。

  [2]a trigger mechanism：触发装置。

  [3]shrink-wrapped retail software：用收缩塑料薄膜包装的零售软件。

  [4]only to：不定式短语表示结果；翻译成“结果……”，如：He made a long speech only to show his ignorance of the subject．他讲一大段话，结果只暴露出他对这门学科一无所知。

  [5]Fifth Generation Systems Fastback Plus：第五代生成系统快速备份。

  [6]Fifth Generation Systems Disklock：第五代生成系统磁盘锁。

  [7]Do not boot from any floppy disk. boot意指“引导”、“启动”。此句译为“不要直接从软盘启动计算机”。

  Choose the best answer for each of the following:

The mysterious tiger has been a symbol of power and strength for centuries. Its power is a【56】to hunters,【57】have tried to kill it to prove their own skill and【58】. In India【59】the nineteenth and early twentieth centuries, large parties of【60】from around the world【61】go out on huge tiger hunts. Hundreds of tigers could be killed in a few weeks. As a【62】of this over-hunting,【63】with loss of habitat(栖息地), the population of tigers in India dropped from about 40,000【64】the turn of the twentieth century to about 2,000 by 1972.

With the help of India and other concerned countries, the World Wildlife Fund【65】Operation Tiger in 1972 to save the tiger【66】dying out. Since then, seventeen tiger preserves (保护区) have been【67】, and the tiger population in India has risen to【68】4,000 and 5,000.

But when people live on the【69】of the tiger preserves, tigers sometimes kill their farm animals and attack people--about 600 people in India have been killed by tigers in the last dozen years.【70】tigers do not eat humans. But "old, wounded and homeless" tigers can become habitual (习惯的) man-eaters. In one area in India, villagers have【71】a clever solution. They wire lifelike human dummies (假人) to electricity【72】the tigers get a(n)【73】shock when they attack. It is hoped that in this way tigers will learn to【74】people. But the conflict between human and tiger【75】. Only if people have enough food, shelter and fuel will the tiger survive in the long run. And only if the tiger and its forest survive will people have a natural world they can return to.

(56)

A．succession

B．challenge

C．guarantee

D．intelligence

One of the aims of teaching science is, through learning, to enable students to develop a complete personality by creativity, honesty, eagerness to acquire knowledge, freedom of speech and thought, and critical assessment. This is an ambitious aim which we unfortunately, rarely consider. During teaching we devote our attention more to the content rather than the aims. We thus see that science is one of the school subjects least favored by students.

The emotional elements of music, dancing, painting, poetry and drama have a strong emotional impact on students. For science to evoke the same feelings, it should be taught with the help of the expressive arts. Unlike traditional didactic approaches, drama also offers a synthesis of visual, kinetic and auditory experiences, apart from the understanding of facts and figures as a result of rational and analytical perception. Drama and other artistic activities can assist in reaching the cognitive goals of the curriculum, as they are effective means of motivation. Isn't there a better chance that students who have developed a love for science will learn it more easily? Science too can be aesthetic, creative and emotional.

By using drama techniques, we facilitate collaboration between the left and right hemispheres of the brain, whereas traditional techniques of teaching science stress only the use of abilities found in the left hemisphere — that is, the analytical perception of scientific notions and phenomena. We allow students to engage in the learning process as full personalities with all their knowledge and abilities. Thus we develop not only logical and mathematical intelligence, but also a wider spectrum of the students' abilities. Our educational experience is largely based on a linear perception of the subject. As students, we have not been used to developing ways of creative and intuitive thinking, especially in scientific subjects. This is why combining expressive arts with science is accepted with difficulty by many.

When using drama in teaching science, we meet paradoxes which can, on the one hand, make the use of drama unsuccessful, and, on the other hand, enable the knowledge of science to be integrated into society and social phenomena that is life in general. Science is taught on the basis of scientific discoveries — laws and explanations of phenomena which are clearly defined and allow no individual or sociological interpretations. Drama, however, is based on developing imagination and different individual interpretations of the same event. Stealing a wallet, for example, will be interpreted as something negative by the owner and as something positive by the pickpocket. Drama broadens our imagination, science is said to narrow it. When observing traditional didactic forms of teaching science, we see that students are required to understand very abstract notions. The notion of the atom or the molecule is demonstrated by concrete means including symbols, various types of atom and molecule models, sketches, experiments, photographs and animated films. These help students to develop their imagination and conceptions which can, individually, be very different despite the fact that they were all taught with the same techniques and materials.

These differences arise from the differences in students' personalities. We must take into account that students have different sensory abilities. They receive information through visual, auditory, and kinetic channels of perception with different intensity. They also have different intellectual abilities. Thus it is easy for some students to logically combine scientific laws with scientific phenomena or visualize what the latter looks like.

The fact that students dislike science class is because science classes

A．develop students' personality by creativity.

B．don't have freedom of speech.

C．concentrate more on knowledge than the development of personality.

D．concentrate more on facts than critical assessment.