第三部分：阅读理解（共20小题；每小题2分，满分40分）
阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项，并在答题
卡上将该项涂黑。
The 2009 outbreak of HINI is a new kind of influenza virus, commonly referred to as “swine flu”. It is thought to be a break of four known kinds of influenza. A virus subtype H1N1: one endedmic(流行病) in humans, one endemic in birds, and two endemic in pigs (swine). The source of the outbreak in humans is still unknown, but cases were first discovered in the U.S. and soon after in Mexico.
According to the U.S. Centers for Disease Control and Prevention(CDC)，it is not yet clear how serious this new virus actually is compared with other influenza viruses, although on May 26 they stated that new cases in the U.S. have probably reached the hightest point, and most cases have so far been mild relative to “seasonal flus”. But because this is a new virus, most people will not have immunity(免疫性) to it, and illness may eventually become more severe and widspread. The H1N1 flu mainly spreads in the same way that regular “seasonal influenza” spreads through the air from coughs and sneezes or touching those infected. It cannot be transmitted from eating cooked pork or by being in close contact with pigs.
As yet there is no vaccine(疫苗) available to prevent infection although companies are in the planning stages for having one available later this year. But there is concern that the virus could vary again over the coming months, leading to a new and potentially more dangerous flu outbreak later in the year, and a vaccine that will be less effective in preventing its spread.
As of May 27, the virus had spread to more than 50 countries; however, over 80% of reported deaths have taken place in Mexico. According to the CDC, the fact that the flu’s infection activity is now monitored more closely may help explain why more flu cases than normal are being recorded in Mexico, the United States and other countries.
1. The 2009 outbreak of H1N1 is thought to .
A.be concerned with four endmics
B.have come from the virus from pigs
C.occur because of unknown virus in Mexico
D.be caused because of people without immunity
2.According to the U.S. Centers for Disease Control and Prevention, ______.
A.most people won’t be infected with the flu
B.the H1N1 will not be too mild to cause many deaths in the world
C.the present situation allows of no optimist
D.H1N1 can be transmitted by touching pigs
3.To make people worried more is that .
A.no effective vaccine can prevent the virus from spreading
B.the virus will mutate in the following months
C.a seasonal influenza will break out
D.the newly-developed vaccine will lose effectiveness
4.From the passage we can learn that .
A.every country is watching closely the spreading of the H1N1
B.more than one-fourth of the deaths from the H1N1 are in Mexico
C.only the United States and Mexico recorded the cased of influenza
D.effective medicine has been produced to cure the H1N1