听力原文：W: Is there anything else we ought to discuss? M: We haven't discussed heating yet. Do you like central heating? W: Yes, but isn't it rather expensive? First costs, I mean--the furnace, and the boiler, all the pipes and radiators? M: That depends on the system. An automatically controlled oil-burning system is rather expensive. W: Electric fires are no cheaper. We have them in the bedrooms, and the electricity bills are always high at the end of the winter. M: What about open fires? W: I like to see a fire. But coal fires do make a lot of work and a lot of dust, too. M: You may have a furnace in the kitchen, and a storage tank upstairs. A furnace that bums coke is much cheaper than one that bums oil. A good one would give you all the hot water you need for the kitchen and for baths, and enough for two radiators in the living room. W: Oh, I know what you mean. They have to be filled twice a day, don't they? M: Yes, and you have to clear out the ashes once a day. W: How much does coke cost? M: They bum three or four tons a year. I'm not sure how much coke costs now--about ￡ 20 a ton, perhaps. W: That's t ￡11.25 or more a week--for all the hot water, and for heating the living room in winter. That's cheaper than any other system I know. M: And very little work, too. W: Great, let's do it. (20)