题目内容：

    Sometimes, you just can’t say no to another spoonful of ice cream and maybe one more after that. Why not? You deserve it.

There’s no need to beat yourself up about it later. The truth is that you were probably bound to do that from the very first spoonful. That’s because there is a switch in your brain, and for whatever reason, it can get stuck in the “on” position.

According to a new study, this impulse (冲动) control may come down to a very specific circuit (回答) in the brain which occasionally produces melanin-concentrating hormone, or MCH—a chemical linked with our desire for food or drugs. And that circuit always says yes.

By manipulating this circuit, it is possible that we might be able to develop cures for overeating that help people stick to a diet without reducing normal appetite or making delicious foods like donuts less delicious.

For their research, the scientists treated rats to a self-serve buffet. Bur the treats were on a timed delivery system, making tasty food every 20 seconds, and only when a rat pressed a lever (杠杆). Hit that lever too early—as impatient test subjects occasionally did—and the counter would start from scratch. Lever-happy rats would have to wait another cycle before the food became available again.

A second experiment offered the rats two dining options. Push Lever A and get an immediate small reward. Pushing Lever B meants waiting for around40 seconds, but the food reward would be much bigger. Guess which lever those impatient rats were most food of? That’s right. They picked the now-now-now switch.

Their impulsiveness, however, rose sharply when scientists gave the rats MCH. These animals become more impulsive. MCH, it seemed, could talk rats into loosening its inhibitions (拘束). The result? More please.

Researchers can now see where that conversation between the brain’s reward system and its impulse control center takes place. The next step will be to map it—and potentially influence the discussion. It may eventually be possible to control a food-eating impulse.

1.Which of the following can best replace the underlined word “manipulating” in paragraph 4?

A.Strengthening. B.Controlling.

C.Classifying. D.Creating.

2.What would happen when a rat pressed a lever earlier than the fixed time?

A.A bigger food reward would appear.

B.Tasty food would be delivered much sooner.

C.Longer time would be needed for food to appear.

D.The lever would be stopped form delivering food.

3.Why did the researchers conduct the experiments?

A.To find out the effect of MCH on animals.

B.To prove rats are also greedy for more food.

C.To study how levers influence rats’ impulse.

D.To show rats and humans have similar impulse for food.

4.What is the best title for the text?

A.What Is the Effect of Your Impulse?

B.What Can You Do to Resist More Food?

C.Why Can’t You Say “No” to Your Impulse?

D.Why Do You Always Give in to One More Mouthful?