Yet I'm the only one watching the animals stare-down. Either nobody else died of a heart attack when the bells went off, or 1 was the only one in the entire hotel who didn't turn the alarm switch to off before going to bed.

　　　The Ark, a hotel shaped like the biblical ark(圣经的方舟), lies in the highlands of Kenya's Aberdare National Park, about 100 kilometers north of Nairobi. At the Ark's prow (船首) are huge windows overlooking a waterhole. Earlier tonight，I'd watched a pack of wolves, buffalos and elephants. And now, at Three or so in the mornings I'm down for the round of rhino bells. The first time, 2.5 hours ago, it was a single black rhino, which came down, got a drink, and left.

　　　I'd have been sorry for the lost sleep. I've already arranged with a guide to take me out at sunrise for the so-called "should-never-missed" bird-watching, where well gel to see 30 species, but really, how many times in your life will you get to wake up and say，"Wow! Rhinor? Isn't that the definition of a pretty good right? Last week we went from Uganda into Kenya，Before I left home, I thought I'd be happy with ten elephants and five or six giraffes on the whole trip.I didn't dare to dream the rhinor.

　　　4．The message that the hotel's bells sent was .

　　　A．a very wise way the author had never heard of

　　　B．hard for the author to remember in detail

　　　C．a matter that all visitors had got used to

　　　D．like conditioned response training for animals

　　　5．What's the author's attitude toward the bell?

　　　A．It's bothering but two bells are welcome.

　　　B．should be turned off whenever it rings,

　　　C．It visitors have a chance to see buffalos.

　　　D．It Is a very bad way to wake the guests up.

　　　6．What does the underlined part "died of a heart atttack" in paragraph 3 mean ?

　　　A．died unexpectedly

　　　B．felt extremely excited

　　　C．felt very uncomfortable and tired

　　　D．suffered from a terrible heart attack

　　　7．What did the author see at about 3:00 a.m.?

　　　A．Two buffalos we me fighting fiercely for food,

　　　B．A rhino and a buffalo were fighting for water.

　　　C．A rhino and a buffalo were staring at each other.

　　　D．A buffalo was teaching its baby to walk freely.

　　　Don't get mad the next time you catch your teenager texting when he promised to be studying. He simply may not be able to resist. A University of lowa(UI) study found teenagers are far more sensitive than adults to the immediate effect or reward of their behaviors. The findings may help explain why the initial rush of texting may be more attractive for adolescents than the long-term pay off of studying.

　　　"For the teenager, 'the rewands are attractive." says Professor Jatin Vaidya，an author of the study. "They draw adolescent. Sometimes, the rewards are a kind of motivation for them. Even when a behavior is no longer in a teenager's best interest to continue, they will, because the effect of the reward is still there and lasts much longer in adolescents than in adults ."

　　　For parents,that means limiting distraction (分心的事情）so teenagers can make better chokes. Take the homework and social media dilemma: At 9 p.m., shut off everything except a computer that has no access to Facehook or Twitter, the researchers advise. "I'm not saying they shouldn't be allowed access to technology," Vaidya says. But some help in netting their concentration is necessary for them so they can develop those impulse-control skills."

　　　In their study,Vaidya and co-author Shaun Vecera note researchers generally believe teenagers are impulsive（冲动的)，make bad decisions，and engage in risky behavior because the frontal lobes（额叶）of their trains are not fully dweloped. But the UI researchers wondered. whether something more fundamental was going on with adolescents to cause behaviors independent of higher-level reasoning.

　　　"We wanted to try to understand the brain's reward system how it change from chilhood to adulthood," Says Vaidya, who adds the reward character in the human brain is easier than decision-making. "We've been tring to understand the reward process in adolescence and Whether there is more to adolescence hehavior than an under-developed frontal lobe,"he adds.For their study ,the researchers persuaded 40 adolescents, aged 13 and 16,and 40 adults, aged 20 and 35 to particpate.

　　　In the future,researchers hope to look into the psychological and neurological（神经学上的）aspects of their results.

　　　8．What does the passage mainly tell us?

　　　A．The initial rush of texting is less attractive for adolescents than the long-term pay off of studying.

　　　B．Always, rewards are attractive to teenagers.

　　　C．Resistance can be controlled well by adolescents.

　　　D．Getting rewards is the greatest motivation for adolescents to study.

9．Which statement agrees with Vaidya's idea?