Different from popular thoughts, colds are not caused by bad weather. Colds
are caused by viruses (病毒)in the body, and you are better out on the snowy
day than you are in a warm room, with your friends, who just may be passing
the virus around. If you feel a chill (寒冷) when you are coming down with a
cold, you are already sick. A chill is an early sign of the cold.
     The virus can spread through air when a cold-sufferer(感冒患者) coughs
or sneezes. Surprisingly, this is not the most usual way of spreading. Many
studies have now shown that most colds are "caught" by hands. A cold-sufferer
rubs her nose, so spreading the virus to her hand. Then a friend comes to visit
her. They shake their hands. The friend then gets something to eat by hand, and
several days later she catches a cold. Although some parents pick up their
children's tissues (纸巾) and carefully throw them away, they fail to wash their
hands. They'll catch the colds, too.
     Cold viruses can also be spread by objects, for example, telephones, plates.
The cold - sufferer as well as other members of the house, by washing their
hands often, will stop the viruses from spreading in a way.