01 Read the following passage and complete the exercises that follow.

Influenza Transmission and Precaution

Influenza is an infectious respiratory virus spread by aerosol droplets emitted by those infected. Infection comes from direct inhalation into the lungs and exposure through the nose and mouth. The spread of influenza from one person to another can occur even before infected individuals experience flu symptoms, but is worst during the height of fever. Children spread influenza more efficiently than do adults. The virus needs moisture and will dry out quickly if exposed to ultraviolet radiation or dry air, which may account for the prevalence of influenza during humid and darker winter weather.

In moist droplets, the influenza virus can survive outside of the body for a time on things like railings, dishes, and doorknobs. Through these it is spread by hand-to-mouth contact when someone touches an object contaminated with the aerosols and then touches his or her own mouth. Sharing cups and utensils with infected individuals increases the risk of infection. For this reason, consistent hand washing with soap and water and properly washing dishes and utensils helps reduce the spread of influenza.

Two major factors in the spread of influenza depend on the strain of the virus and its rate of mutation, since flu strains constantly mutate as they compete with host immune systems. Influenza B and C are milder forms, but influenza A produces more serious cases of illness. Pandemics occur when a virulent strain of flu infects millions of people around the world, typically due to new mutations that have migrated from other animals to humans. The 1918 Spanish Flu outbreak, for instance, resulted from a mutated strain related to avian influenza that caused hemorrhage and other unusually severe symptoms.

The three kinds of influenza spread at different rates, but all of them are spread through the coughing and sneezing of infected individuals. Hygienic precautions like hand washing and avoiding proximity to sick people during the height of their infection reduces the spread of the virus. Vaccination can slow down influenza infection rates and protect vulnerable populations.

Vaccination prevents the spread of influenza in common forms, particularly of influenza B, but it does not guarantee protection from the spread of new mutations. It is recommended for the elderly, who are at greater risk of serious complications.

While how well the flu vaccine works can vary, there are a lot of reasons to get a flu vaccine each year.

●Flu vaccination can keep you from getting sick with flu.

●Flu vaccination can reduce the risk of flu-associated hospitalization, including among children and older adults.

a. A 2014 study showed that flu vaccine reduced children's risk of flu-related pediatric intensive care unit （PICU） admission by 74% during flu seasons from 2010-2012.

b. Another study published in the summer of 2016 showed that people 50 years and older who got a flu vaccine reduced their risk of getting hospitalized from flu by 57%.

●Flu vaccination is an important preventive tool for people with chronic health conditions.

a. Vaccination was associated with lower rates of some cardiac events among people with heart disease, especially among those who had had a cardiac event in the past year.

b. Flu vaccination also has been shown to be associated with reduced hospitalizations among people with diabetes （79%）and chronic lung disease （52%）.

●Vaccination helps protect women during and after pregnancy. Getting vaccinated can also protect a baby after birth from flu. （Mom passes antibodies onto the developing baby during her pregnancy.）

a. A study that looked at flu vaccine effectiveness in pregnant women found that vaccination reduced the risk of flu-associated acute respiratory infection by about one half.

b. Studies show that flu vaccine in a pregnant woman can reduce the risk of flu illness in her baby by up to half. This protective benefit was observed for up to four months after birth.

●Flu vaccination also may make your illness milder if you do get sick.

Getting vaccinated yourself also protects people around you, including those who are more vulnerable to serious flu illness, like babies and young children, older people, and people with certain chronic health conditions. If flu sufferers rest at home and avoid public places until recovery, they are less likely to expose others to the virus.

Getting a flu vaccine each year is the best way to prevent the flu. Antiviral drugs are an important second line of defense against the flu. These drugs must be prescribed by a doctor. In addition, good health habits, such as covering your cough and frequently washing your hands with soap, can help prevent the spread of the flu and other respiratory illnesses.

（Source: https://en.wikipedia.org/wiki/Influenza）

02  Read the following passage and then check your understanding.

Controversial Bird-Flu Research Published: 

How Worried Should We Be?

A highly controversial research paper on bird flu was released today by the journal Nature. It shows that a particularly troublesome strain of avian influenza, designated H5N1, which has been worrying public health officials for more than a decade, has the potential to become a human pandemic. In other words, H5N1 bird flu, which so far has been highly lethal to humans but has not acquired the ability to spread easily among us, could do so at any time.

The researchers, under the direction of Yoshihiro Kawaoka at the University of Wisconsin at Madison, crossed an H5N1 virus with the H1N1 pandemic virus of 2009, which spread like wildfire from one end of the world to another. The 2009 pandemic, you'll recall, caught public health officials by surprise but luckily turned out to be mild. Kawaoka's lab-made hybrid virus spreads among ferrets by airborne droplets expelled during the course of respiration—just as human influenza viruses such as the 2009 pandemic strain spread from person to person. Kawaoka's concoction does not kill ferrets, and probably wouldn't kill humans, but the feat is troubling because it demonstrates that an H5N1 virus that can spread among humans is most likely possible. (We don't know for sure because it was tested only on ferrets, not humans, of course.)

The known H5N1 viruses that currently exist in nature do not attach to the upper respiratory tracts of humans, so most victims caught the virus from close contact with birds. And there is reason to think that a highly lethal but poorly transmissible virus like H5N1 would change in the process of becoming transmissible—that in acquiring the ability to spread, the virus would have to make genetic tradeoffs that compromise its ability to kill. For instance, one reason that the Ebola virus doesn't spread widely among humans is that it is too efficient—mortality is as high as 90 percent—which means victims die before they can infect many others. We do not know, however, to what extent a human-transmissible H5N1 virus would have to make this tradeoff. Scientists differ widely in their opinions on this point.

The strain that Kawaoka concocted in his lab seems to be mild—it made ferrets sick, but didn't kill them. Even if this virus is not itself dangerous, however, it demonstrates that an H5N1 strain could one day arise that turns into a worrisome human pathogen. As Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, has pointed out, a human-transmissible virus with a lethality rate 20 times lower than current wild strains of H5N1 would still kill more efficiently than the 1918 flu. The degree to which H5N1 is potentially dangerous to humans is the subject of much speculation.

In part because of all the uncertainty, the biosecurity community has been in an uproar ever since the Kawaoka paper came to their attention last year. (Things really got stirred up when Ron Fouchier of Erasmus Medical Center in Rotterdam made remarks at a conference in Malta about similar work on H5N1 transmissibility, which he submitted to Science but has been held up by the Dutch government.) Many security experts believe no work on H5N1 transmissibility among mammals should have been conducted in the first place, and that the world would be a safer place if information about the results of the Kawaoka and Fouchier experiments and their methods were never disseminated. (Although the National Science Advisory Board for Biosecurity voted to green-light the publication of both papers, that vote came only after the results and the methods used to make the viruses had been disseminated to hundreds of people in the course of the standard pre-publication review process; holding up publication at that point, in this age of Wikileaks, probably would have been futile.) Recently the U.S. government has called for risk-benefit assessments of pathogens on its select agent list before research is conducted (H5N1 is on that list), but compliance is left to the funding agencies. Some biosecurity experts are calling for further restrictions in H5N1 research on transmissibility among mammals, such as limiting the work to labs with the highest biosafety standards.

Many scientists believe this would be a mistake. They think that research on what could possibly make H5N1 deadly to humans is too urgent to be put under onerous security constraints. Kawaoka was interviewed in 2010, during the course of research for the book, The Fate of the Species (which Bloomsbury releases on May 22). At the time, Kawaokoa was deeply worried about the danger of H5N1 bird flu. There had been outbreaks among poultry in 1997 and again in 2004 in Hong Kong, and the virus had shown other signs of restlessness—it had killed wild birds, which usually carry H5N1 without symptoms, and it had shown a propensity to spread outward from east Asia, despite the culling of millions of chickens and other poultry. How long would it be before nature's roulette wheel produced a human version of H5N1?

Researchers so far have already found natural strains of H5N1 that have acquired some of the genetic changes that Kawaoka's recent paper identifies as necessary for transmissibility among ferrets. The research that Kawaoka and other influenza scientists are conducting certainly poses a risk, as some biosecurity experts have pointed out. The experiment reveals that nature is conducting every day, as H5N1 viruses mutate and borrow genetic material from other viruses, is also potentially dangerous. Which should we fear most? On this question there are many opinions, but no definitive answers.

(Source: Cited from "Controversial Bird-Flu Research Published: How Worried Should We Be?" By Fred Guteri)

04 Put the following into Chinese or vice versa.