Cells in the basic ranking list are divided into categories. How many categories are t

H fulfil band and layer thresholds, what cells should be prioritized and in what order？()

A. A, B, F, G, E, and C

B. G, E, B, A, C, and F

C. G, E, B, and A

D. B, A, F, G, E, and C

E. A, B, E, and G

A.两个cells的overlap的区域描述了一个basic service set

B.网络描述了一个extended service set

C.再每个CELL中的AP必须被配置成使用channel 1

D.为了确保连通性，重叠区域必须小于10%

E.两个访问点应该被配置成工作在不同的频道

根据以下内容回答题：

Scientists know that there are two basic approaches to prolonging life（延长寿命），one approache is the elimination of the diseases that generally affect older people—diseases such as cancer，heart attack and stroke．（1）is the delay of the process of growing-old the（2）of the body． In recent years scientific researchers（3）much time in the study of the process of aging．They believe that，within a few years，they will develop the knowledge and the（4）to delay the aging process for lo to 15 years．The result will be that more people will live longer，more healthful lives．At present，scientists believe that with the right diet，exercise，medical（5），and mental attitude many people can live to he l00 years old． Gerontologists（老年学专家），people who（6）studies of the problems of growing old，are investigating（7）body cells slow down and（8）die．They feel that delaying this slowing down process（9）help postpone death．In a number of American universities，scien-tists are studying the activity of cells，the effects of diet and internal body temperature on aging．If their studies are successful，the results should help（10）the quality of life for older people in the next few years，as well as increase the life span of the next generation．

1.

A.Others

B.Another

C.The other

D.One more

Medicine Award Kicks off Nobel Prize Announcements

Two scientists who have won praise for research into the growth of cancer cells could be candidates for the Nobel Prize in medicine when the 2008 winners are presented on Monday, kicking off six days of Nobel announcements.

Australian-born U. S. citizen Elizabeth Blackburn and American Carol Greider have already won a series of medical honors for their enzyme research and experts say they could be among the front-runners for a Nobel.

Only seven women have won the medicine prize since the first Nobel Prizes were handed out in 1901. The last female winner was U. S. researcher Linda Buck in 2004, who shared the prize with Richard Axel.

Among the pair's possible rivals are Frenchman Pierre Chambon and Americans Ronald Evans and Elwood Jensen, who opened up the field of studying proteins called nuclear hormone receptors.

As usual, the award committee is giving no hints about who is in the running before presenting its decision in a news conference at Stockholm's Karolinska Institute.

Alfred Nobel, the Swede who invented dynamite, established the prizes in his will in the categories of medicine, physics, chemistry, literature and peace. The economics prize is technically not a Nobel but a 1968 creation of Sweden's central bank.

Nobel left few instructions on how to select winners, but medicine winners are typically awarded for a specific breakthrough rather than a body of research.

Hans Jornvall, secretary of the medicine prize committee, said the 10 million kronor (US $1.3 million) prize encourages groundbreaking research but he did not think winning it was the primary goal for scientists.

"Individual researchers probably don't look at themselves as potential Nobel Prize winners when they're at work," Jornvatl told The Associated Press. "They get their kicks from their research and their interest in how life functions."

In 2006, Blackburn, of the University of California, San Francisco, and Greider, of Johns Hopkins University in Baltimore, shared the Lasker prize for basic medical research with Jack Szostak of Harvard Medical School. Their work set the stage for research suggesting that cancer cells use telomerase to sustain their uncontrolled growth.

Who is NOT a likely candidate for this year's Nobel Prize in medicine？

A．Elizabeth Blackburn.

B．Carol Greider.

C．Linda Buck:

D．Pierre Chambon.

s the【79】of the disease that generally【80】older people-disease such as cancer, heart attack and strokes.【81】is the delay of the process of growing old--the【82】of the body.

In recent years scientific researchers【83】much time in the study of the process of aging. They believe that, within a few years, they will develop the knowledge and the【84】to delay the aging process for 10 to 15 years. The result will be that more people will live longer, more healthy lives.【85】, scientists believe that with the fight diet, exercise, medical【86】, and mental attitude many people can【87】100 years old.

Gerontologists, people who【88】studies of the growing old, are investigating why body cells show and【89】die. They feel that delaying this slowing down process would help postpone death. In a number of American universities, scientists are【90】the activity of cells, the effects of diet and internal body temperature【91】aging. If their studies are successful, the results should help【92】the quality of life for older people in the next few years,【93】increase the life span of the next generation.

(46)

Genetic Engineering

Genetic engineering began when the DNA molecule (分子), the most basic unit of life, was first described in 1953 by James Watson and Francis Crick. An understanding of DNA led to the altering of normal cell reproduction. Experiments with altering human cells began in 1970. In one of the first ex- periments, patients were injected with a virus that would produce a life-saving enzyme, but their bodies would not accept it. In 1980 patients with a rare but fatal blood disease were injected with a pu- rified gene that was cloned through DNA technology. Another failure.

Genetic engineering got a legal boost (激励) in 1980. The U. S. Supreme Court said that a patent could be granted on a genetically engineered "oil-eating" bacterium (细菌). This bacterium would help clean up oil spills. The ruling encouraged companies to invent new life forms, and three important medical products were quickly developed.

Human interferon (干扰素)-a possible solution to some cancers and viral disease A newly engineered bac-terium produced hurnan interferon as a by-product. This new product reduced the cost of interferon.

Human growth hormone-for children whose bodies do not grow to normal height. An expensive growth hormone (荷尔蒙) was previously produced from human cadavers, but by changing the genetic make-up of the single-cell bacterium E. coli, and affordable growth hormone could be produced.

Human insulin (胰岛素)-for the treatment of diabetes. People with diabetes used to rely on a beef-or pork-based product until 1982. Now insulin can be manufactured by genetically altered bacteria.

Advances in genetic engineering have continued, though they constantly must be weighted against the safety of procedures. There is clearly much more to discover.

This passage is mainly about

A.the effects of altering cells

B.the human growth hormone

C.insulin resistance

D.U. S. Supreme Court rulings

recognize anything in it at all. Ask them whether they saw an animal and they consider themselves to be making a futile guess. Yet those guesses are right much more often than they are wrong. That is because the brain can carry out immediate visual processing even when it does not have time for any cognitive back-chatter. A neuroscientist trying to understand how people recognize objects would thus start with this simplest of systems.

That is the purpose of Dr. Serre's computer. His project is nothing less than ad attempt to reverseengineer the relevant part of the brain. That part is the ventral visual pathway. Anatomy shows that it is organized into numerous areas. Experiments on monkeys, in which researchers have recorded what excites individual nerve cells in each of these areas, give strong hints about how it works.

The pathway is hierarchical. Signals from the retina flow to the most basic processing area first; the cells in that area fire up others in the next area, and so on. Those in the first area are fussy. They react to edges or bars in particular orientations. By combining their signals, however, cells in the second area can respond to comers or bars in any orientation. And so the system builds up. Cells in the final area can recognize general things, animals included.

Dr. Serre considered his computer's processing units analogous to nerve cells, and he organized them into areas, just as they are in real brains. Then he let the machine learn in much the same way that babies do. First he mimicked early development when nerve cells are plastic. At this stage babies' brains tune their nerve cells to visual features according to how common those features am in the world around them. That is why kittens raised so that they see only vertical lines have brains that look different from those raised in an environment with purely horizontal ones. Dr. Serre's processor developed sensitivities in a similar fashion when he showed it lots of photographs. That stage complete, he then told the computer when what it "saw" contained an animal, and when it did not.

The result was a model that closely imitates the ventral visual pathway. Processing units in each area are sensitive to the same set of features as nerve cells in the brain's analogous areas, and they are linked together as they are in the brain. This artificial recognition system correctly distinguishes photographs containing animals from those without creatures 82% of the time; Dr. Serre's students get it right 80% of the time. Moreover, his computer and his volunteers tend to slip up on the same images — and turning photographs on their sides makes poorer animal-recognizers out of both, by roughly the same amount.

The phrase "cognitive back-chatter" in paragraph 1 probably means ______.

A．communication with others

B．response to certain stimulation

C．instant processing of information

D．recognizing pictures or objects

A．Free From Particular Average

B．With Particular Average

C．War Risk

D．All R isks