In their book Time to Eat the Dog: The Real Guide to Sustainable Living, Robert and Brenda Vale say keeping a mediumsized dog has the same ecological impact as driving 10,000 km a year in a 4.6 liter Land Cruiser. “We’re not actually saying it is time to eat the dog. We’ re just saying that we need to think about and know the ecological impact of some of the things we do and that we take for granted.” Constructing and driving the jeep for a year requires 0.41 hectares of land, while growing and manufacturing a dog’s food takes about 0.84 hectares — or 1.1 hectares in the case of a large dog such as a German shepherd. Convincing flesheating cats and dogs to go vegetarian for the sake of the planet is a nonstarter, the Vales say. Instead they recommend keeping “greener”, smaller, and more sustainable pets, such as goldfish, chickens or rabbits. The book’s playful title, and serious suggestion that pet animals may be usefully “recycled”, by being eaten by their owners or turned into pet food when they die, may not appeal to animal fans. Annoying as the idea may be, the question is valid given the planet’s growing population and limited resources, Robert Vale said. “Issues about sustainability are increasingly becoming things that are going to require us to make choices which are as difficult as eating your dog. It’s not just about changing your light bulbs or taking a cloth bag to the supermarket,” he said. “It’s about much more challenging and difficult issues,” he added. “Once you see where cats and dogs fit in your overall balance of things, you might decide to have the cat but not also to have the two cars and the three bathrooms and be a meat eater yourself.” 56. The authors gave their book the playful title to________. A. make it amusing                    B. create a vivid image C. show　writing skills                 D. arouse people’ s concern 57. In Paragraph 3 the writer mainly wants to tell us________. A. the amount of consumed land  B. the neglected ecological impact C. some familiar examples  D. some actual figures 58. What does “sustainability” mean according to the passage? A. Going vegetarian.  B. Raising cats and dogs. C. Using a cloth bag.  D. Keeping a greener life. 59. Who may not like the idea of “recycling” pet animals? A. Manufacturers.                  B. Drivers.  C. Animal fans.                     D. The authorities. 60. What do the authors think of living a sustainable life? A. Challenging.          B. Inspiring.          C. Inviting.         D. Touching.