阅读理解。
Influenza (流行性感冒)has been with us a long, time. According to some Greek writers on
medical history, t
he outbreak of 412 BC was of influenza. The same has been suggested of the
sickness that swept through the Greek army attacking Syracuse in 395 BC. Flu is a disease that
moves most quickly among people living in crowded conditions, hence it is likely to attack armies.
In April 1918, flu broke out among American troops stationed in France. It quickly spread
through all the armies but caused relatively few deaths. Four months later, however, a second
outbreak started which proved to be a killer. It killed not only the old and already sick but also
healthy young adults. It went through every country in the world, only a few distant islands in the
South Atlantic and the Pacific remaining untouched. Before the great outbreak ended, it had killed
at least 15 million people.
Medical science is still not certain what hit us in 1918. The virus of influenza (流感病毒) was
not found until 1933, so all that today can be said about the 1918 outbreak is the kind of antibodies
it produced.
The first big advance was also made in 1933, then a team of British doctors found the type A
influenza virus. In 1940, a doctor of the United States found type B. Later type C was found, along
with many subgroups of type A and B. Vaccines (疫苗) were prepared and used widely by the
armies during the Second World War to prevent outbreaks.
The flu virus proved trickier (奸诈) than most. A vaccine good against one type gave a protection
against another. Indeed type A virus changes its nature so quickly that a perfectly good vaccine may
lose its value because of the change. This increases the need for the speedy discovery of flu outbreaks,
so that stocks(家畜) of the right vaccine can be prepared quickly after an outbreak. Starting such a
warning system was one of the first things done by the World Health Organization. .
1.Why is influenza easier to attack armies?
A. Because it moves very quickly.
B. Because it spread through Greek army long ago .
C. Because it spread through the crowded most quickly.
D. Because an army moves more often.
2.How many types of influenza have been found excluding subgroups?
A. One type.
B. Two types.
C. Three types.
D. Four types
3.How many people were killed in the flu outbreak of 1918?
A. One million.
B. Several million.
C. Seven million
D. Fifteen million.
4.Which of the following is true according to the passage you have just read?
A. Before 1936 people didn't know what caused influenza.
B. A Group of American doctors first discovered the types of influenza
C. All kinds of vaccine can not prevent every kind of influenza virus.
D. The earliest outbreak of disease mentioned happened in the year 412 BC.