Different from popular thoughts, colds are not caused by b________(1) weather. Colds are caused by
viruses in the body, and you are b________(2) out on a snowy day than you are in a warm room, with your
friends, who just may be spreading the virus a________(3). If you feel a chill (寒战) when you are coming
down with a cold, you are already s________(4). A chill is an e________(5) sign of the cold.
     The virus can spread t________(6) air when a cold-sufferer (感冒患者) coughs or sneezes. Surprisingly,
this is the most usual way of spreading. Many studies have now s________(7) that most colds are "caught"
by hands. A cold-sufferer rubs her n ________(8) and spread the virus to her hand. Then a friend comes to
visit her. They s________(9) their hands. The friend then gets something to eat by hand, and several days
later, she catches a cold. A________(10) some parents pick up their children's tissues (纸巾) and carefully
throw them away, they fail to wash their hands. They'll catch colds, too.
     Cold viruses can also be spread by objects, such as telephones, plates and keyboards. The cold-sufferer
as well as other m________(11) of the family, by washing their hands often, will p________(12) the viruses
from spreading in a way.