Few people like changing their habits，good or bad．Whether it is smoking，drinking or over-eating，they（15）___"enjoying"them to the end．
On every packet of cigarettes（香烟），people are warned against the（16）___of smoking："Warning：Cigarette Smoking Is Dangerous to Your Health"．（17）___，millions of them start smoking or go on smoking．Why？
Facts show that families and surroundings（环境）play a very important part in（18）___ smokers．All those smokers come from smoking families or have smoking（19）___or relatives．Films and TV plays also play a part．People（20）___their"heroes"on TV drinking alcohol（酒）or smoking cigarettes．"Heroes"seem to fear（21）___，neither killing themselves nor killing others with alcohol and cigarettes．If they are not afraid of the harm of smoking and drinking，（22）___should common people be afraid？
The simple warning on the cigarette packet does not influence smokers'habits，Even（23）___warnings，like showing pictures of smokers who have died of cancer，don't seem to work．
Knowing and believing seem to be two（24）___things．If smoking is really as harmful as doctors say，it is time for smokers to think about it and try to give it up!