题目内容
B
Although we already know a great deal about flu, and although the World Health Organizations is constantly collecting detailed information from its chain of flu reference laboratories throughout the world, it is extremely difficult for epidemiologists, who study infectious diseases, to predict when and where the next flu epidemic will occur, and how serious it will be.
There are three kinds of flu virus, known as A, B and C. flu C virus is relatively stable and causes mild infections that do not spread far through the population. The A and B types are unstable, and are responsible for the epidemics that cause frequent concern. Following any virus attack, the human body builds up antibodies （抗体） which can be changed into immunity to that type of virus but a virus with the ability to change its character is able to bypass this protection. Variability（可变性） is less developed in the flu B virus, which affects only human beings. As flu B virus may cause a widespread epidemic but will have little effect if introduced into the same community soon afterwards, since nearly everyone will have built up antibodies and will be immune. The flu A virus, which affects animals also, is extremely unstable and is responsible for some of the worst outbreaks of the disease, such as the world epidemic, of 1918&1919, when about half the world's population were infected and about twenty million people died, some from pneumonia caused by the virus itself and some from secondary complication caused by bacteria. Accurate prediction is difficult because of the complication of the factors. A particular virus may be related to one to which some of the population have partial involved immunity. The extent to which it will spread will depend on factors such as its own strength, or virulence （病毒性）, the ease with which it can be transmitted and the strength of the opposition it encounters （遇到）. Scientists, however, have a reliable general picture of the world situation.
55. Which of the following is the most appropriate title for the passage?
A. Symptoms of Flu B. Man Vs Flu Virus
C. WHO: The Major Organization against Flu Virus D. Variability of Flu Virus
56. What does the author say about the flu B virus?
A. B Virus is relatively stable and causes mild infections that do not spread far through the population.
B. B Virus is unstable, and is responsible for the epidemics that cause frequent concern.
C. B virus is extremely unstable and is responsible for some of the worst outbreaks of the disease.
D. B virus has a very developed variability, and it affects only human beings.
57. Which of the following is NOT mentioned as a factor contributing to the extent to which a virus spreads?
A. The strength of the virus. B. The ease with which the virus can be transmitted.
C. The strength of the opposition. D. The immunity the virus can bring about.
58. This article is quite probably ________.
A. a piece of news B. a special science report
C. an introduction to a book D. a scientific fiction
【小题1】B
【小题2】B
【小题3】D
【小题4】B
期末金牌卷系列答案
轻松课堂标准练系列答案| 完形填空。 | ||||
| It was on a winter morning, near Oxford, Maryland, that I set the breakfast table beside the huge window, which _1_ the Tred Avon River.The snow decorated the shore in white.For a moment I stood quietly against the bookcase, appreciating what the night's snow had _2 . 3 I leaned forward and peered (盯着看) close to the frosted window."It really is!" I cried out loud."There is a goose out there! " I _4_ to the bookcase and pulled out a pair of binoculars (望远镜).Into their sights came the 5_ of a large Canada goose, very still, its wings folded tight to its sides, its _6_ frozen to the ice.Then from the dark sides, I saw a line of swans.They crossed 7 the west of the broad river, moving _8_ to the east. As I _9_, the leader swung to the right, and then the white _10_ of birds become a white circle.It floated from the top of the sky downward.At last, as easy as feathers coming to earth, the circle _11 the ice. The swans _12_ the frozen goose! Amazingly, those bills (啄) began to work on _13 .The long necks were lifted and curved down, _14_. It went on for a long time.At last, the goose was free and _15_ its big webbed (有蹼的) feet slowly.The goose _16 its wings as far as they would go.The swans took off and _17 on their eastward journey, in perfect formation, to their secret destination._18_ them, rising with incredible speed and joy, the goose moved into the sky.I watched them _19 they disappeared over the tips of the farthest trees.Only then did I realize that tears were running down my cheeks.This is a true story.I do not try to interpret it here.I just often 20 it in the bad moments, and tell myself, "If so for birds, why not for man?" | ||||
|
