In 1957 a doctor in Singapore noticed that hospitals were treating an unusual number of influenza-like cases. Influenza is sometimes called “flu” or a “bad cold”. He took samples from the throats of patients in his hospital and 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 type A and B, each of them having several subgroups. With the instruments at the hospital the doctor recognized that the outbreak was due to a virus in group A, but he did not know the subgroup. Then he reported the outbreak to the World Health Organization (WHO) in Geneva. WHO 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, doctors began the standard tests. They found that by reproducing itself with very high speed, the virus had grown more than a million times within two days. Continuing their careful tests, the doctors checked the effect of drugs against all the known subgroups of virus type A. None of them gave any protection. This, then, was something new, a new influenza virus, against which the people of the world had no help whatever. Having found the virus they were working with, the two doctors now dropped it into the noses of some specially selected animals, which get influenza much as human beings do. In a short time the usual signs of the disease appeared. These experiments proved that the new virus was easy to catch, but that it was not a killer. Scientists, like the general public, call it simply Asian flu. The first discovery of the virus, however, was made in China before the disease had appeared in other countries. Various reports showed that the influenza outbreak started in China, probably in February of 1957. By the middle of March it had spread all over China. The virus was found by Chinese doctors early in March. But China was then not a member of WHO and therefore didn’t report the disease to it. Not until two months later, when the virus spread to Singapore, did the news of the outbreak reach the rest of the world. By this time it was started on its way around the world. 1. As the doctor in Singapore found the disease, he ________.A) set his patients apart from othersB) reported the outbreak to WHO C) was keen on naming the diseaseD) found the subgroup of the virus2. The truth about the virus in this passage was that it ________.A) was a weak typeB) was a derivation from othersC) could reproduce with high speed D) had been stored in a fridge3. Which statement is TRUE about the influenza according to the passage?A) It could only be spread among children.B) It had been identified many years before.C) There were no effective drugs for it. D) Animals were alert to this disease.4. According to the experiment on animals, we can find that ________.A) the flu was easy to cause death to animalsB) the flu has a more serious effect on animalsC) there was no significant sign of the fluD) the flu was serious but not deadly 5. It can be inferred that the first measure for WHO to track a disease such as influenza is to ________.A) set up an efficient reporting service B) set apart adequate time to study the factC) cooperate with every doctor wellD) train more highly skillful experts