题目内容：

 

Teenagers’ acting selfishly could be down to the wiring in their brains, scientists said recently．

Teenagers hardly use the area of the brain that analyzes other’s emotions and thoughts when considering a course of action．They are also less likely to consider their own emotions than adults do, said scientist Dr Sarahjayne Blakemore, from University College London.

Many areas of the brain change dramatically during the teenage years, with one part ---- the medial prefrontal cortex(内侧前额叶皮层) ---- continuing to develop way beyond adolescence．This is an area at the front of the brain associated with higher-level thinking, empathy (同情), guilt and understanding other people’s motivations(动机)．

The researchers say they have now found that, when making decisions about what action to take, the medial prefrontal cortex is underused in teenagers．Instead, a back area of the brain involved in sensing and imagining actions, takes over．

Dr．Blakemore said: “Thinking methods change with age．As you get older you use more or less the same brain network to make decisions about your actions but the important difference is that the distribution of that brain activity shifts(改变方向) from the back of the brain to the front．

“We think that a teenager’s judgment of what they would do in a given situation is driven by the simple question: ‘What would I do?’．Adults, on the other hand, ask: ‘what would I do, given how I would feel and given how the people around me would feel as a result of my actions?”

In the study, teenagers and adults were asked questions about the actions they would take in a given situation while their brains were scanned using functional Magnetic Resonance Imaging．A second piece of research showed teenagers were less likely to think about how they would feel in another person’s shoes.

Dr Blakemore concluded: “ It is clear that teenagers are dealing with, not only massive hormonal shifts(激素变化), but also important neural(神经系统的) changes.”

1.When teens decide to take action, they ________．

       A．ask too many questions

       B．hardly use the brain network

       C．use the brain activity more than adults

       D．hardly consider other people’s emotions

2.What’s the meaning of the underlined word “underused”?

A．often used        B．being developed   C． wrongly used D．not used enough

3.The purpose of writing this passage is to ______________．

       A．blame teenagers for their selfish behavior

       B．advise teenagers not to be selfish

       C．show how to change a selfish teenager

       D．explain why teenagers act selfishly