听力原文：Narrator Listen to part of a lecture in a geography class. Professor Were gonna look at the effects of global warming on a particular country to get this thing into context and I want to look at Australia, a country with 12 000 kilometers of coastline. Theres a whole series of problems. What I mean by that is uh... in a country like this, well, there are floods, droughts, cyclones, bushfires, landslides, earthquakes, soil degradation and...so on you name it, weve got it! OK. Now on your handouts theres a list of reading materials which you should have a look at in preparation for your tutorials next week. Id particularly recommend The Greenhouse Effect by Henderson-Sellers and Blong—theyre very good on the Australian situation. If you...for general background, Lovelocks is good, and the book edited by Pearman offers a nice review of greenhouse issues in Australia. Ive put them in Special Reserve, so you shouldnt have any trouble finding them. Okey...so Im gonna start today by looking at one of the most serious effects of a change in the global temperature that is, a rise in sea-level and...as I said, Im gonna concentrate today on the effects this would have on the Australian context. If we assume that therell be a meter or so rise in sea-level over uh...say, the next fifty years but unfortunately, the situations not so clear because weve got to take into consideration a variety of scenarios such as increased precipitation at the poles which might actually cause a fall in sea-level. Anyway, taking this figure of a meter rise over, say, the fifty or so years, what are we going to see? Well, well see an effect on flooding of structures on the coast you know, house, sea walls, ports and the whole infrastructure of roads, rails, power lines and cables, and so on. Secondly, were gonna be seeing shoreline retreat in some low-lying areas. The sea will move inland in areas...such as the Gulf of Carpentaria. To put it another way, in low-lying urban areas, your nice beachfront apartment may just end up floating away and your parking lot two hundred meters from the beach will end up as a prime waterfront estate. Most Australian cities are on the coast and in the case of Brisbane in particular well, take a look at this overhead. Thats roughly the area indicated by the blue line thats gonna be affected with a one meter rise in sea-level. So if youre thinking of investing in real estate in this area, take my advice dont! Again, though, its difficult to predict the situation. Local conditions in some areas may actually increase the deposit of materials affecting an extension of the land. But whichever way you look at it therell be a fairly radical change to many eco-systems, and if you recall last weeks lecture on change well, were really opening a can of worms here. Apart from coastal flooding, we should also expect the penetration of salt water systems into estuaries, rivers and lagoons. If you think about the Myall Lakes system for example well, the whole freshwater complex could be reunited with the sea. One of the most serious direct consequences of this for man of course would be seepage into the groundwater in other words, the seas salt water would enter the water table under the land. This would cause salinity in sources of drinking water and irrigation. Thirdly, we should expect to see a rise in temporary flooding of coastal areas. Im not talking about flooding as a result of increased rainfall, though thats another consideration Ill come to it later. For now, Im talking about flooding as a result of higher tides. Think about it, the swamping of the storm water drainage system. Whats that gonna do to the street youre living in? So, in summary, as weve seen youve got coastal flooding, destruction of coastal structures, shoreline shifts and salt water intrusion. Ill come back to some of these later, but for now, lets move on and look at tropical cyclones. Everyone remembers Tracy. Or maybe you dont because that is going back to 1974. Im getting a bit old. Now get ready to answer the questions. You may use your notes to help you answer. 18. What is the lecture mainly about? 19. Which of the following is NOT mentioned as a direct effect of the rise in sea-level? 20. What does 'temporary flooding of coastal areas' mean? 21. What does the professor imply when she says this? Professor ...your parking lot two hundred meters from the beach will end up as a prime waterfront estate. Listen again to part of the lecture. Then answer the question. Professor But whichever way you look at it therell be a fairly radical change to many eco-systems, and if you recall last weeks lecture on change—well, were really opening a can of worms here. 22. Why does the professor say this? Professor well, were really opening a can of worms here. Listen again to part of the lecture. Then answer the question. Professor ...but for now, lets move on and look at tropical cyclones. Everyone remembers Tracy. Or maybe you dont because that is going back to 1974. Im getting a bit old. 23. What does the word 'Tracy' most probably refer to?Narrator Listen to part of a lecture in a geography class. Now get ready to answer the questions. You may use your notes to help you answer. What is the lecture mainly about?