题目内容：

If you know something is bad for you, why can’t you just stop? About 70% of smokers say they would like to stop. Drug and alcohol abusers (滥用者) struggle to give up the bad habits that hurt their bodies and destroy families and friendships. And many of us have unhealthy weight that we could lose if only we would eat right and exercise more. So why don’t we do it?

Some scientists have been searching for answers. They’ve studied what happens in our brains as habits form. They’ve found answers to why bad habits, once formed, are so difficult to kick. And they’re developing ways to help us make the changes we’d like to make.

Habits are a normal part of life, and are often helpful. “ We wake up every morning, shower, comb our hair or brush our teeth without being aware of it,” Volkow says. We can drive along familiar routes without really thinking about the directions. “When behaviors become automatic(不加思索的), it gives us an advantage, because the brain does not have to perform the action on purpose.” Volkow says. This frees up our brains to focus on different things.

One way to kick bad habits is to focus on your unhealthy habits. Then try your best to stop them. For example, habits can be linked in our minds to certain places and activities. You could develop a plan, say, to avoid walking down the hall where there’s a candy machine. Try to avoid going places where you’ve usually smoked. Stay away from friends and situations linked to problem drinking or drug use.

Another helpful way is to replace unhealthy habits with new, healthy ones. “It doesn’t work for everyone,” Volkow says. “But certain groups of patients who have a history of taking a drug can do something else like running and it helps them stay away from drugs.”

1.In the first paragragh the writer mainly wants to tell us ______.

A. we should stop something bad for us

B. most smokers would like to stop smoking

C. bad habits are really difficult to give up

D. eating right and exercise more can lose weight

2.Scientists studied what happened in our brains as habits form in order to______.

A. find answers to solve the problem

B. find ways to form good habits

C. kick their own bad habits

D. help us see how bad habits form

3. If you want to kick bad habits you’d better_______.

A. focus on them on purpose

B. go to the places linked with them

C. do something linked with them

D. ask your friends for help

4.What is the main idea of the passage?

A. Breaking bad habits.

B. Forming good habits.

C. Finding reasons for bad habits

D. Replacing bad habits with good ones.