18．On a dark night，11-year-old Joe was playing hide-and-seek with his friends in the backyard when he thought he saw Magellan-a huge housecat．However，when the cat suddenly jumped on his head，Joe found it turned out a young cougar（美洲獅）．He backed away from the animal，then turned and ran inside the house．
Cougar encounters （遭遇） like this one are becoming very common in the U．S．Most people assume that's because cougar populations are growing，or because the big cats are coming into closer contact with the expanding web of human suburbs．But Professor Robert Wielgus at Washington State University argues that poorly designed hunting policies might be causing an increase in cougar-human conflicts．
Wielgus's research teams have been fitting the big cats with radio collars and monitoring their movements．They find that the cougar population is actually decreasing rapidly and almost no male cougars are over four years of age．And a study shows that the heavily hunted area has five times as many cougar complaints as the lightly hunted area-even though the density（密度）of cougars is about the same in both areas．
Wielgus suspects that hunting policies，which allow older males to be killed to keep cougar populations in check，were the culprit and teenage cougars in the heavily hunted area may be responsible for most of the trouble．To test his theory，he adds two more groups of cougars to the tracking program-one in a heavily hunted area and another in a comparable but lightly hunted area．He concludes that heavy hunting indeed almost wipes out older males and the population structure in the heavily hunted area shifts toward younger animals．
With these findings，Wielgus believes without adults to keep them under control，the disorderly teens are more likely to come into conflict with humans，farm animals and pets．
Wielgus's ideas don't sit well with everyone．"Hunting definitely does cause lots of teenage males to flow in，but I don't yet see solid proof that they are more likely to cause trouble than older cats，"says the University of Montana's Robinson．"In many cases，the new arrivals have been squeezed （擠出） out of remote wilderness habitat and forced into areas where they are more likely to encounter humans．I think humans are primarily responsible for all the interaction you see．We're moving into these areas where cougars and deer are，"according to Alldredge，a researcher at the Colorado Division of Wildlife．
We may not understand what makes 18-year-old males more likely than 48-year-old men to do dangerous things，Wielgus says，but we know that the world would be a different place，if teenagers were in charge．
29．The passage begins with a story toA．
A．lead into the topic
B．describe an incident
C．show the author's attitude
D．warn of the dangers of cougars
30．The underline word"culprit"in Para.4is closest in meaning toC．
A．effect
B．evidence
C．cause
D．a(chǎn)im
31．Which of the following is true？B
A．Alldredge agrees hunting results in the arrival of lots of teens．
B．Robinson doubts age is a key factor in human-cougar conflicts．
C．Alldredge believes killing older males may cause a bigger threat．
D．Robinson holds humans are to blame for the fall of older males．
32．What might Wielgus suggest to reduce cougar attacks？D
A．Driving teenage cougars back into their natural habitat．
B．Getting people to move out of the areas where cougars are．
C．Preventing children from playing in the backyard by themselves．
D．Improving hunting policies to ensure a healthy cougar population．
