A、They mainly live on the ground. B、They are sensitive to dangers. C、The females do not have a call. D、The males are more diffic

Many dogs are very hard-working animals. They have been helping people for thousands of years. Dogs protect our homes. They help people with disabilities. They team up with rescue workers in search-and-rescue operations.
And now, dogs can add another job to their resumes— finding endangered animals! The official title for this kind of work is conservation detection dog. Conservation experts in Australia are training dogs to use their sense of smell. The aim of the job is to find some of the country’s most endangered creatures. Luke Edwards is a dog owner and trainer. He is training two border collies, named Rubble and Uda, to become conservation detection dogs. He says that border collies are good for this kind of work because they have a great sense of smell. The dogs also have great mental and physical strength to work long hours. Recently, the dogs went on their most difficult job yet— finding the Baw Baw frog. This is the call of the male Baw Baw frog. This frog is one of Australia’s most endangered animals. The work is difficult mainly because of the search area. Just to get to the place, or site, where the frogs live, the dogs and their trainers must walk far distances through alpine forests. “Going out to the sites at Mount Baw Baw is probably one of the hardest areas I’ve had to search in. Just to get out to the site, we’re trekking through alpine forests.” It is difficult but important work. A deadly fungus has killed nearly all of Australia’s Baw Baw frogs. In fact, scientists say these creatures could disappear in the next five to 10 years. Zoos Victoria is a group set up to protect wildlife. Conservation experts there claim that since 1980 the deadly fungus has killed off 98% of the Baw Baw frogs. So, Zoos Victoria is trying to save the frog. Experts there raise them and have them reproduce. They call it their captive breeding program. Deon Gilbert is a frog expert at Zoos Victoria. He says that detecting the frogs in the wild can be very difficult because they mainly live underground. The females are even more difficult to find. They, unlike the male Baw Baw frogs, do not have a call. He adds that the dogs Rubble and Uda had no trouble in finding the frogs. “This species is incredibly difficult to detect in the wild. The dogs were able to locate the exact site where the frogs were calling from much, much quicker than we could do just by using ears.”
Questions 19 to 22 are based on the recording you have just heard.
19. What is the talk mainly about?
20. What is the most difficult part of finding Baw Baw frogs?
21. What do scientists say about Baw Baw frogs?
22. What does Deon Gilbert say about Baw Baw frog?