Influenza， or flu（流感）， is a type of virus． It spreads from one person to another quickly． When someone who has the flu coughs or sneezes， little droplets from their lungs （肺） spread out into the air．Anyone nearby can get sick． Even a person who touches something with the virus and then touches his or her mouth， eyes， or nose， can become infected（感染）．

    The outbreak of the 1918 influenza infected about 500 million people worldwide． It killed from 20 million to 50 million people． It was first seen in Europe， the United States， and parts of Asia．It then spread quickly around the world． Many people who became sick were young， healthy adults．At the time， no treatments worked in the prevention of the spread of the killer flu． People were ordered to wear masks． Schools， theaters and other public places were closed．

    When the first wave（波＞in the spring of 1918 hit， it didn't seem serious． People who were infected felt the usual flu symptoms（症状）， which are chills， fevers， and feeling tired． Those who got sick generally got better after several days． Not many died． However， a second， highly contagious（传染的）wave of influenza appeared in the fall of that same year． Victims died shortly after they were infected ﹣ within hours or days． Their skin turned blue and their lungs were filled with liquid（液体），making it very difficult to breathe．

    By the summer of 1919， the flu pandemic（大流行病） came to an end． Sick people had either got well or died． Almost 90 years later， in 2008， researchers announced they'd discovered why the 1918 flu was so deadly． The flu virus inflamed （使…恶化）the lungs， causing them to fill with liquid．

    Since 1918， there have been several other influenza pandemics， although none has been quite as deadly．

（1）What information about the 1918 flu is mentioned in the passage？　　

A． The reason why it was so deadly．

B． The reason why it ended．

C． The change it caused to medical research．

D． The place in which it was last seen．

（2）All the people that were infected with the 1918 flu　　．

A． had blue skin that led to their death

B． had touched someone with the virus

C． died as their lungs were filled with liquid

D． had the virus in their bodies that made them sick

（3）Which of the following statements about the 1918 flu is TRUE according to the passage？　　

A． Wearing a mask was the best way to treat it．

B． A younger person had a lower risk of being infected with it．

C． People expected the coming of its second wave， but couldn't stop it．

D． It was deadlier than any other influenza pandemic in modern history．