Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the   correct answer to each of the questions.

The goal of Internet-based encyclopedia Wikipedia (www.wikipedia.org) is to give everyone on the planet access to information. Like other encyclopedias, Wikipedia contains lots of information:    more than

2.5 million articles in 200 different languages covering just about every subject. Unlike other encyclopedias, however, Wikipedia is not written by experts, but by ordinary people. These writers are not paid and their names are not published. They contribute to Wikipedia simply because they want to share their knowledge.

Encyclopedias began in ancient times as collections of writings about all aspects of human knowledge. The word itself comes from ancient Greek, and means “a complete general education”. Real popularity for encyclopedias came in the nineteenth century in Europe and the United States, with the publication of encyclopedias written for ordinary readers. With the invention of the CD-ROM, the same amount of information could be put on a few computer discs. Then with the Internet, it became possible to create an online encyclopedia that could be constantly updated, like Microsoft’s Encarta. However, even Internet-based encyclopedias like Encarta were written by paid experts. At first, Wikipedia, the brainchild of Jimmy Wales, a businessman in Chicago, was not so different from these. In 2001, he had the idea for an Internet-based encyclopedia that would provide information quickly and easily to everyone. Furthermore, that information would be available free, unlike other Internet encyclopedias at that time.

But Wales, like everyone else, believed that people with special knowledge were needed to write the articles, and so he began by hiring experts. He soon changed his approach, however, as it took them a long time to finish their work. He decided to open up the encyclopedia in a radical new way, so that everyone would have access not only to the information, but also to the process of putting this information online. To do this, he used what is known as “Wiki” software (from the Hawaiian word for “fast”), which allows users to create or alter content on web page. The system is very simple: When you open the web site, you can simply search for information or you can log on to become a writer or editor of articles. If you find an article that interests you – about your hometown, for example – you can correct it or expand it. This  process goes on until no one is interested in making any more changes.

The user of Wikipedia can do all of the following EXCEPT                                       .

A. have access to information

B. determinate the website 

C. modify information

D. edit information

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the   correct answer to each of the questions.

Although they are an inexpensive supplier of vitamins, minerals, and high-quality protein, eggs also contain a high level of blood cholesterol, one of the major causes of heart diseases. One egg yolk, in fact, contains a little more than two-thirds of the suggested daily cholesterol limit. This knowledge has caused egg sales to plummet in recent years, which in turn has brought about the development of several alternatives to eating regular eggs. One alternative is to eat substitute eggs. These egg substitutes are not really eggs, but they look somewhat like eggs when they are cooked. They have the advantage of having low cholesterol rates, and they can be scrambled or used in baking. One disadvantage, however, is that they are not good for frying, poaching, or boiling. A second alternative to regular eggs is a new type of egg, sometimes called 'designer' eggs. These eggs are produced by hens that are fed low-fat diets consisting of ingredients such as canola oil, flax, and rice bran. In spite of their diets, however, these hens produce eggs that contain the same amount of cholesterol as regular eggs. Yet, the producers of these eggs claim that eating their eggs will not raise the blood cholesterol in humans.

Egg producers claim that their product has been portrayed unfairly. They cite scientific studies to back up their claim. And, in fact, studies on the relationship between eggs and human cholesterol levels have brought mixed results. It may be that it is not the type of egg that is the main determinant of cholesterol  but the person who is eating the eggs. Some people may be more sensitive to cholesterol derived from food than other people. In fact, there is evidence that certain dietary fats stimulate the body's production of blood cholesterol. Consequently, while it still makes sense to limit one's intake of eggs, even designer eggs, it seems that doing this without regulating dietary fat will probably not help reduce the blood cholesterol level.

What is the meaning of  'back up'?

A. reverse

B. advance

C. block

D. Support