题目内容：

Most people looking for ways to quit smoking worry about weight gain, and with good reason. Smokers who quit tend to pack on an average of 5 pounds after they stop smoking cigarettes. A new study, published by the journal Science, explains why this happens.

The new research explains that nicotine appears to combine with appetite-regulating neurons (调节食欲的神经元) in the brain, besides the receptors (感受器) that bring about addiction. These neurons help regulate how much food gets consumed, but under the influence of nicotine, they lose their self-control. This is why when smokers quit, they tend to eat more and gain weight.

The researchers believe that their discovery will lead to the development of drugs that aim at nicotine receptors on brain cells that control appetite. In the future, weight gain may no longer be a reason for smokers to delay the decision to kick the habit, but that’s no reason to wait. Nicotine-replacement treatment, while not for everyone, can help. Here are a few more ways to quit smoking and stay slim.

Drink water. To improve metabolic (新陈代谢的) rates, make half of those glasses ice water. Juice can be too high in calories, something you’ll want to keep an eye on your journey toward being a slimmer non-smoker. Plan your snacks. Healthy snacks help keep your metabolism working, so you continue to burn calories while stopping wild hunger pain, or fake hunger.

Keep moving. Exercise kills two birds with one stone. It helps you burn calories and prevents you from eating when you’re not truly hungry. It’s also a feel-good stress reliever (缓解物). Focus on your fitness and how being healthy makes you feel. Make exercise a goal and think of quitting as your reward for being physically fit.

1.Which of the following changes people’s appetite according to the new research?

A. Nicotine.    B. Appetite-regulating neurons.

C. The receptors that bring about addiction.    D. The food that has been consumed.

2.By saying “but that’s no reason to wait” in Paragraph 3, the author means that ________.

A. some new drugs are going to be developed soon

B. nicotine-replacement treatment cannot help everyone

C. losing weight should be an excuse for smoking

D. some ways to quit smoking while staying slim are available

3.The author believes that ________.

A. ice water can improve metabolic rates    B. smokers should eat fewer snacks to keep slim

C. stress can lead to fake hunger    D. exercise can help one eat less

4.The purpose of the text is ________.

A. to introduce the result of a new study

B. to explain the reason why smokers become slim

C. to prove the possibility of being a slim non-smoker

D. to tell us ways to quit smoking without gaining weight