填空题

Most smokers want to stop smoke. Many of 76. ______
them have tried more than once but failed. 77.______
Although they know smoking may kill them and 78.______
cause a serious illness yet they can give it up. 79.______
The reason to it is that tobacco contains nicotine 80.______
that is a drug which gets one into habit of smoking. 81.______
Because you start taking the drug, it is hard to stop. 82.______
If you go without it for an hour or two, it 83.______
begin to feel bad. The only thing can stop 84.______
you feeling bad is the drug containing in cigarettes. 85.______