（新教材）人教版（2019）高中英语必修第一册Unit 3 Video Time ppt课件（含视频）.zip

To learn to know the Karsts of China The Karsts of China: A Vertical Journey Karsts are found in many places in southwestern China. Rock climbers like to go there to enjoy climbing and challenge themselves. 喀斯特地貌 喀斯特地貌，又称岩溶地貌，是具有溶蚀 力的水对可溶性岩石（大多为石灰岩）进行溶 蚀作用等所形成的地表和地下形态的总称。喀 斯特（Karst），意为岩石裸露的地方。我国喀 斯特地貌分布广、面积大，主要分布在碳酸盐 岩出露地区，面积约91至130万平方千米。其中 以广西、贵州、云南和四川、青海东部所占的 面积最大，是世界上最大的喀斯特区之一。 我国西南地区之所以喀斯特地貌分布广泛 ，最主要的是这里有其发育的主体。大量的碳 酸盐岩、硫酸盐岩和卤化盐岩在流水的不断溶 蚀作用下，在地表和地下形成了各种奇特的溶 洞。这种奇妙的自然作用，用化学方程式可以 表现为：CaCO3+CO2+H2O=Ca(HCO3)2。 溶有碳酸氢钙的水如果受热或遇周围压强突然 变小时，其中溶解的碳酸氢钙就会分解，重新 变成碳酸钙沉积下来，此时的反应方程式为： Ca(HCO3)2 =CaCO3+CO2+H2O。西南 地区气候湿润，降水量大，地表径流相对稳定 ，流水下渗作用连续，加之降水使流水得以更 新和有效补充，因此岩溶作用得以延续进行。 我国喀斯特现象的文字记载，可追溯到 2400年前。距今约400年前的徐宏祖（徐霞客） 已专门研究并记述了南方喀斯特地形与洞穴。 喀斯特地貌是大自然给人类留下的宝贵礼 物，无论是峰林、石芽还是溶洞、峡谷，它们 不仅为我国的科学研究和资源探索带来可贵资 料，还为旅游业的发展带来无限生机。而阳朔 十里画廊，群峰挺拔，峰丛林立，风姿多态的 喀斯特景观星罗棋布，地下洞系密集交织。地 表的秀丽山林与地下的钟乳石笋交相辉映，构 成了大自然“奇峰、奇洞、美石”的奇观。 Read the introduction of Karsts and discuss the questions below. Karsts are rock formations made of limestone. They have been sculpted by wind and water and millions of years of erosion into these beautiful natural sculptures. One of the most famous places in the world for karsts is Guilin. The karsts there provide a lot of exciting opportunities to rock climbers. 1. Would you like to have a go at karst climbing? Why or why not? 2. What can rock climbing bring to climbers? Complete the sentences below with the adjectives in the box. 1. For me, its important not just to go and see these _ landscpaes but to interact with them, too. amazing, natural, adventurous, spectacular, unexplored, gymnastic natural 2. The stone here offers up _, athletic movement, but it can also be very _, sometimes dangerous, but always beautiful. 3. This is what we love to doto come to these beautiful _ areas and climb and explore and push ourselves mentally and physically. amazing, natural, adventurous, spectacular, unexplored, gymnastic spectacular adventurous gymnastic 4. China is relatively _ and new to climbers and to adventurers who want to go out and see something new and _. amazing, natural, adventurous, spectacular, unexplored, gymnastic amazing unexplored 1. Describe your feelings after watching the video. How are they the same as or different from the feelings the climber describes when he talks about climbing the karsts? 2. What is your opinion of extreme sports such as rock climbing? Is it something worthwhile to do? Why or why not? Discuss the questions. Revise this unit.