It is difficult to give up smoking for two main reasons.First is the power of nicotine（尼古丁），found naturally in tobacco（烟草）leaves.Second,people often smoke as a routine or habit,and giving up can be hard because it requires a change of pattern.People smoke often when they're stressed.There are luckily products people can buy to help them give it up,including nicotine patches （贴片）.
Addiction is one of the biggest challenges for people to give up.Nicotine is a drug that is naturally in the roots and leaves of the tobacco plant,and its presence tells us why smoking these leaves is so popular：the drug makes people feel good,and can reduce one's pressure,at least in the short term.People breathe in it when smoking cigarettes and other similar products,and from there it enters the bloodstream quickly.It travels through the heart and to the brain,where pleasant feelings are produced.Once these centers of the brain become used to the drug,people will begin to thirst for it.Over time most people build up a tolerance to the drug.In this sense,the longer a person waits,the harder it will likely be to quit.
Most people find that they can't give up smoking unless they really want to,and it often takes a lot of willpower and determination（决心）.Certain medicine can help reduce some worst side effects,and many also find that it helps to slowly reduce nicotine addiction rather than stop it all at once.Nicotine patches people can wear are often helpful,as these can deliver controlled amounts of the drug into a person's blood.



What can we learn from the text？ ______

A. Tobacco can relieve stress completely.
B. People smoke only when feeling stressed.
C. There are products to help smokers give up smoking.
D. It is the best way to quit smoking suddenly.

Why is smoking tobacco popular with some people？ ______

A. It helps people look cool.
B. It can make people healthy.
C. It smells and tastes good.
D. It makes people feel fine.

What may the author agree with？ ______

A. Stopping producing tobacco.
B. Quitting smoking as early as possible.
C. Buying much medicine to quit smoking.
D. Quitting smoking is easy for most people.

What is the last paragraph mainly about？ ______

A. Why it is hard to quit smoking.
B. What can be done to quit smoking.
C. Why it is impossible to quit smoking.
D. How to help others quit smoking.