共用题干第二篇<br><br>Study Says Dogs Can Smell Cancer<br><br>Dogs are known for their sense of smell.They can find missing people and things like <br>bombs and illegal drugs.Now a study suggests that the animal known as man's best friend <br>can even find bladder（膀胱）cancer.<br>Cancer cells are thought to produce chemicals with unusual odors（气味）. <br>Researchers think dogs have the ability to smell these odors,even in very small <br>amounts,in urine（尿）.The sense of smell in dogs is thousands of times better than <br>in humans.<br>The study follows reports of cases where,for example,a dog showed great interest in <br>a growth on the leg of its owner.The mole（痣）was later found to be skin cancer.<br>Carolyn Willis led a team of researchers at Arnersham Hospital in England.They <br>trained different kinds of dogs for the experiment.The study involved urine collected from <br>biadder cancer patients,from people with other diseases and from healthy people.<br>Each dog was tested eight times.In each test there were seven samples for the dogs <br>to smell.The dog was supposed to signal the one from a bladder cancer patient by lying <br>down next to it,<br>Two cocker spaniels（短腿长毛垂耳小猎犬）were correct fifty-six percent of the time.<br>But the scientists reported an average success rate of forty-one percent.<br>As a group,the study found that the dogs chose the correct sample twenty-two out of fifty-four times.That is almost three times more often than would be expected by chance alone.<br>The British Medical Journal published the research.In all,thirty-six bladder cancer <br>patients and one hundred and eight other people took part.<br>During training,all the dogs reportedly even identified a cancer in a person who had <br>tested healthy before the study,Doctors found a growth on the person's right kidney(肾）.<br>Bladder cancer is the ninth most common cancer worldwide.The International Agency <br>for Research on Cancer says this disease kills more than one hundred thousand people each <br>year.Doctors say cigarette smoking is the leading cause of bladder cancer. The dogs' average success rate was