[单项选择]In 1957 a doctor in Singapore noticed that hospitals were treating an unusual number of influenza-like (像流感的) cases. Influenza is sometimes called "flu" or a bad cold". He took samples from the throats of patients and in his hospital was able to find the virus (病毒) of this influenza.
There are three main types of the influenza virus. The most important of these are types A and B, each of them having several sub-groups. With the instruments at the hospital the doctor recognized that the outbreak was due to a virus group A, but he did not know the subgroup. He reported the outbreak to the World Health Organization in Geneva. W.H.O. published the important news alongside reports of a similar outbreak in Hong Kong, where about 15-20% of the population had become ill.
As soon as the London doctors received the package of throat samples, they began the standard tests. They found that by reproducing itself at very high speed, the virus had multiplied more than a million times within
A. This influenza can cause death if not treated immediately.
B. The number of the influenza virus can grow very rapidly.
C. The people who got the disease recovered soon.
D. The London doctors did not take the virus seriously at first.