A、They are liable to attack. B、They like to smell people. C、They are as smart as cats. D、They are independent. A

Are you a dog person? Maybe you have one at home and enjoy taking it for walks and curling up with it on the sofa. Personally, I’m not that kind of person. (22) For me they’re aggressive, smelly animals that need constant care and lack the independent nature and intelligence that cats have. But given the life-saving skills that some dogs possess, maybe I should give them a second chance.
    (23) To some, a perfect dog might be one that looks cute, is loyal and sits when it’s told. But to really be man’s best friend, they need to do something useful. (24) Some breeds that have amazing sense of smell are put to good use as detection dogs. They are trained to use their senses to detect substances such as explosives and illegal drugs. You’ll often see them at airports or working with police out on the streets.
    Other types of working dogs including guide dogs and hearing dogs provide a life-saving service to their owners. Some dogs can alert emergency services when their owner has a seizure. And there are clever dogs that have been trained to provide affection and comfort to people in hospitals, retirement homes or schools.
    New uses for dogs are being discovered all the time. The dog is in fact a highly sophisticated sensor. Evolution has given him this highly sensitive nose. (25) It’s this incredible ability that has led to the UK’s National Health Service assessing whether dogs can be used to detect early stage cancer. It’s vital for improving survival rates.
Questions 22 to 25 are based on the passage you have just heard.
22. What does the speaker think of dogs in the beginning?
23. Which is a feature a perfect dog should possess according to some people?
24. What can we learn about dogs with good sense of smell?
25. What is crucial to improving survival rates of cancer patients?