Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 35 to 42
PANDEMIC DISEASES
Diseases are a natural part of life on earth. If there were no diseases, the population would grow too quickly, and there would not be enough food or other resources, so in a way, diseases are natural ways of keeping the Earth in balance. But sometimes they spread very quickly and kill large numbers of people. For example, in 1918, an outbreak of the flu spread across the world, killing over 25 million people in only six months. Such terrible outbreaks of a disease are called pandemics.
Pandemics happen when a disease changes in a way that our bodies are not prepared to fight. In 1918, a new type of flu virus appeared. Our bodies had no way to fight this new flu virus, and so it spread very quickly and killed large numbers of people. While there have been many different pandemic diseases throughout history, all of them have a new thing in common. First, all pandemic diseases spread from one person to another very easily.
Second, while they may kill many people, they generally do not kill people very quickly. A good example of this would be the Marburg virus. The Marburg virus is an extremely infectious disease. In addition, it is deadly. About 70 -80% of all people who get the Marburg virus died from the disease. However, the Marburg virus has not become a pandemic because most people die within three days of getting the disease. This means that the virus does not have enough time to spread a large number of people. The flu virus of 1918, on the other hand, generally took about a week to ten days to kill its victims, so it had more time to spread.
While we may never be able to completely stop pandemics, we can make them less common. Doctors carefully monitor new diseases that they fear could become pandemics. For example, in 2002, and 2003, doctors carefully watched SARS. Their health warnings may have prevented SARS from becoming a pandemic.
According to paragraph 1, how are diseases a natural part of life on Earth?
