21.It's hard to refuse hamburgers,French fries,potato chips.And all of the other junk food that seemed to call out to us.However,eating too much junk food can harm your body,particularly if you are between the ages of 10 and 19. "Junk food shapes teenagers'(青少年) brains in ways that impair their ability to think,learn and remember.It can also make it harder to control impulsive(沖動的) behaviors," said Amy Reichelt.A brain and nutrition specialist at Western University,Canada."It may even up a teen's risk of unhappiness and anxiety." Reichelt and two other researchers reviewed more than 100 studies about how poor food choices can influence(影響) teenagers' brains.They found teenagers are more sensitive(敏感的) than any other age group to man-made foods with a lot of fat and sugar and their brains are not yet fully formed. Teenagers' brains are still developing the ability to assess(評估) risks and control actions.The prefrontal cortex(前額皮質)is a part of brain.It tells us we should not eat chips all the time and helps us resist the urge.However,this region is the last to mature-it doesn't fully develop until we are in our early 20s. Meanwhile,teen brains get more excited from rewards.The parts of the brain that make us feel good when we do something pleasurable-like eating tasty foods-are fully developed by the teens year. In fact,these regions are even more sensitive when we are young.That is because dopamine(多巴胺),a natural chemical that lifts our mood when we experience something good,is especially active in teen brains. Therefore,the teen brain has two actions against it when it comes to resisting junk food."It has a stronger drive for rewards and less self-regulation(自我調節),"said Reichelt. So what's the best way to say no to junk foods?Researchers suggest exercise.When we exercise,the brain's reward system(系統) becomes less sensitive to food clues.Exercise also pushes the body to make a protein(蛋白質).It helps brain cells grow and form connections between the prefrontal cortex and other brain regions.The prefrontal cortex thus can work better to help us make wise decisions and control our impulses.
(1)The word "impair" in paragraph 2 probably means
. A.improve B.weaken C.change D.influence (2)According to the passage,teenagers are more sensitive to
. A.Milk B.Salad C.Ice-cream D.Strawberries (3)What is the writer's main purpose in writing the last paragraph?
A.To discuss why teenagers prefer the junk food. B.To stress that it is difficult for teens to resist the junk food. C.To suggest that teens do more exercise to resist the junk food. D.To question whether our mood could suffer from eating junk food. (4)What can we learn from the passage?
A.Dopamine can lift our mood when we exercise. B.Fat and sugar in the junk food is bad for our health. C.The prefrontal cortex is fully developed by the teen years. D.Having more junk food may cause unhappiness in teens.
22.Getting through the darkest days A "dark moment" refers to the most difficult time in your life.Have you experienced any dark moments before?How did you get through it? Bob When I got to Junior 1,I was sad to find out that all of my classmates had studied everything before the class started.During class,everyone knew the answers to our teacher's questions but I did not.I came last in the first test.So I looked for ways of learning online.For example,for history.drawing the timeline on paper helped me a lot.My grades then got a lot better.I'm very happy for myself. Gina My classmates bullied(霸凌) me in primary school.That was my darkest time.During military training(軍訓),I didn't have much life experience.So my roommates laughed at me a lot.When we were back in school,I became friends with a girl.But I soon found out that she was not my real friend.She said bad things about me behind my back.Then my teacher heard me and took care of the bullying.That's why I speak up when people bully my classmate now. Frank When I was in the sixth grade,I moved to a new city.At that time,I felt bad every day.My classmates all knew each other and had their small groups.I had no friends and lost interest in everything.My grades also became the worst in the class.Those were my darkest days.Later,I made a friend.He made me open up,and I started to talk to more people.Also,I came to get used to the weather in the city.Step by step.I felt better and better.
(1)What did Bob do to improve his grades?
(2)Who helped Gina get through the darkest time?
(3)When did Frank lose interest in everything?
(4)Have you had a dark moment?If you experience a dark moment,what can you do to get it through?