老托福听力93篇(33-34)-Today I want to talk about33Today I want to talk about the Earth's last major climatic shift, at the end of the last ice age. But first, let's back up a moment and review what we know about climatic change in general. First, we defined "climate" as consistent patterns of weather over significant periods of time. In general, changes in climate occur when the energy balance of the Earth is disturbed. Solar energy enters the Earth's atmosphere as light and is radiated by the Earth's surface as heat. Land, water, and ice each affect this energy exchange differently. The system is so complex that, to date, our best computer models are only crude approximations and are not sophisticated enough to test hypotheses about the causes of climatic change. Of course, that doesn't keep us from speculating. For instance, volcanic activity is one mechanism that might affect climatic change. When large volcanoes erupt, they disperse tons of particles into the upper atmosphere, where the particles then reflect light. Since less light is entering the system of energy exchange, the result would be a cooling of the Earth's surface. Of course, this is just one possible mechanism of global climate change. In all probability, a complete explanation would involve several different mechanisms operating at the same time.【生词摘录】1. climatic: adj. connected with the weather in a particular area 气候的2. ice age: one of the long periods of time, thousands of years ago, when ice covered many northern countries 冰川期，冰河时代3. consistent: adj. always having the same beliefs, behavior, attitudes, quality etc(信仰、行为、态度、品质等)一贯的，一致的;始终如一的4. disturb: v. to interrupt someone so that they cannot continue what they are doing by asking a question, making a noise etc 干扰，打扰;使中断5. radiate: v. if something radiates light or heat, or if light or heat radiates from something, it is sent out in all directions 辐射(光或热);(向四面八方)发射6. crude: adj. not developed to a high standard or made with great skill 粗制的7. approximation: n. [C]a number, amount etc that is not exact, but is almost correct 概算，近似值8. hypothesis: n. [C]plural hypotheses, an idea that is suggested as a possible way of explaining a situation, proving and idea etc, which has not yet been shown to be true 假设，假说9. speculate: v. to think or talk about the possible causes or effects of something without knowing all the facts or details 猜测，推测10. disperse: v. if something disperses or is dispersed, it spreads over a wide area(使)消散;(使)分散11. cooling: n.[U]the process of becoming cooler; a falling temperature 冷却34I know you're anxious to get your permits and get started. But there're just a few things I'd like to mention that might help you avoid trouble during your stay. First of all, make sure you carry adequate water. You'll need it if you're hiking, especially in this heat. A good rule of thumb is to bring one gallon per person per day this time of year. Don't try to rely on the park's natural springs to supply all your water needs. And please, do not use soap in the springs. It's your responsibility to protect the park's natural features. For those of you staying beyond the weekend, make sure that you set up camp well away from dry creekbeds. We may get some heavy rainfall, and those creekbeds could quicklybecome filled with water, and you and all your equipment might end up washed downstream. When you pick up your permits, you'll also get a park services booklet. It'll tell you everything you need to know about the hiking trails. They vary in length, of course, but most of them are under five miles—relatively easy day hikes. Remember, if you're hiking solo, make sure you let someone know you're going and when they can expect you back. And . . . uh, for your own safety, we recommend that you not climb rock faces. A lot of the rock throughout the park is very unstable. One final word: watch out for poisonous snakes. Rattlesnake activity is at its peak this time of year, especially at night. For your own good, we recommend wearing protective clothing and carry a flashlight after dark.【生词摘录】1. hike: v. to walk a long way in the mountains or countryside 徒步旅行，远足2. rule of thumb: a rough method of calculation, based on practical experience(根据实际经验的)粗略的计算方法3. gallon: n. [C]a unit for measuring liquids, equal to 3.785 litres 加仑(等于3.785升)4. feature: n. [C]a part of something that you notice because it seems important, interesting, or typical 特点，特征，特色5. creekbed: n. [C]6. downstream: adv. in the direction the water in a river or stream is flowing 顺流而下;向下游方向7. booklet: n. [C]a very short book that usually contains information 小册子8. trail: n. [C]小径9. solo: adv. 单独地10. unstable: adj. 不牢固的, 不稳定的11. rattlesnake: n. [C]响尾蛇12. flashlight: n. [C]手电筒。