题目内容：

Ever wondered whether punishment actually makes people cooperate (合作)? A team of scientists created an experiment to figure it out and the results were pretty unexpected.

To understand what they found, you have to know why these scientists were studying punishment. They were trying to figure out why people cooperate when it’s often so easy to profit at others expense. Why don’t friends steal from each other? Why do parents bother to feed their children? If the answer to these questions is obvious to you, congratulations, you are ahead of scientists. They’re still trying to figure it out.

In this experiment, researchers had 225 Chinese students play a game, where if the students cooperated, they’d all get a number of points. But if one defected (变节) and everyone else cooperated, the defector would get a lot of points, and the cooperators would lose out. This game represents a lot of real life situations where you struggle with a decision: work together and do OK, or run off with the rewards, ruining everybody else’s day.

This is actually a pretty ordinary economic experiment. But the researchers added two changes to see if they could mimic(糢拟〉the real world better. Change one: some students played many rounds together, so they’d learn who they could trust. Change two: people could punish each other, sacrificing a point or two to destroy another player’s score.

In the end, the researchers found that playing multiple rounds made people cooperate more, which definitely mimics human society. But the whole punishment thing led to a surprise: punishing didn’t actually make people cooperate more. In fact, it made them cooperate less.

So the scientists still don’t know why people cooperate, though it looks like it has more to do with groups sticking together than it does with punishment.

1.What does the underlined word “it” in Paragraph 2 refer to?

A. Why friends don’t steal from each other.

B. Why researchers are studying punishment.

C. Why people always profit at others’ expense.

D. Why people cooperate rather than take advantage of others.

2.What happened to a defector in the experiment?

A. He lost out.    B. He benefited more.

C. He got punished.    D. He became the leader.

3.What conclusion is drawn from the experiment?

A. Punishing helps people realize their mistakes.

B. Cooperating is a win-win policy to all.

C. Punishment won’t work as expected.

D. People who choose to cooperate are selfless.

4.What might be the best title for the text?

A. Does punishing people actually work?

B. Why is punishment applied to cooperation?

C. How can punishment contribute to cooperation?

D. What is the best way to make punishment effective?