105. The following appeared in a health newsletter.
"According to a recent study, people with many social ties report catching colds less often than do people with few social ties. Consequently, researchers conclude that having an active social life probably helps strengthen the immune system. The researchers note that catching a cold—one of a family of highly contagious viruses—gives the cold-sufferer temporary immunity to that virus in the future, but not to the many other related viruses. Merely being exposed to a new cold virus, however, is not enough for a person to catch a cold, since a strong immune system can successfully fight off some new viruses. Thus, in order to prevent catching a cold, people should strengthen their immune systems by becoming more active socially."
1. The newsletter assumes that to prevent catching a cold, people should strengthen their immune systems by becoming more active socially.
2-1. The active social life may not helps strengthen the immune system.
2-1-a. The active personality of the active people can make their habits healthier. They will exercise more, manage their meals, for a balanced diet.
2-1-b. It doesn't mean that they will meet people with a contagious virus to build the immunity to that virus.
2-2. However, to build the immunity of a virus, one has to catch in a cold.
2-2-a. This is not preventing catching a cold, but stepping inside to catch a cold.
2-2-b. Even though one gets the immunity, it only prevents the exact virus, and other viruses can not be prevented.
3. So, to strengthen their immune system, people should have to change their habitants.