根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。
Ali is from a Middle Eastern country. He now stays in the USA. He smokes a lot of cigarettes every day. He has smoked for nine years. Ali says, “I tried to quit smoking in my hometown, but it was impossible. My parents smoke. My brothers smoke. All my friends smoke. At parties and at meetings, almost all the men smoke. Here in the United States, not as many people smoke.    ”
Many smokers are like Ali: they want to stop smoking.           They know it can cause cancer and heart disease. But it is difficult for them to give up smoking because cigarettes have a drug in them. The drug is nicotine. People who smoke a lot need nicotine.
     The nicotine makes him sick. In a few days, the smoker's body is used to the nicotine, and he feels fine. Later, the smoker needs nicotine to keep feeling fine. Without nicotine, he feels bad.
      Many people who quit will soon smoke again. At a party or at work they will decide to smoke "just one" cigarette. Then they will smoke another cigarette, and another. Soon they become smokers again.      

A．It is very hard to quit smoking.

B．It will be easier to change the smoking habit here.

C．Thus nicotine makes smokers addicted to cigarettes.

D．The smokers know that smoking is bad for their health.

E. When a person first begins to smoke, he usually feels terrible.
F. Maybe there is only one easy way to quit smoking: never start.
G. But it is said that medicine is needed to stop them from smoking.