初中英語河北加拿大版學(xué)生用書 25

[by:喜歡tingclass.net，請把tingclass.net告訴你QQ上的5位好友，多謝支持！] [00:00.00]聽力課堂網(wǎng) UNIT 4 [00:03.08]Lessons 25~32 [00:08.05]Look into Science! [00:11.89]Lesson 25: [00:16.64]Keep the Candle Burning!Science is so interesting! [00:23.72]I'm sure you'll like this experiment! [00:28.68]When you do this experiment,you will learn something about air! [00:34.64]What do you need? [00:37.80]a candle [00:40.67]a candleholder [00:44.02]a big glass jar [00:48.14]a shallow dish with water [00:52.58]matches [00:55.43]To make a candle burn,you "light" it. What do you use? [01:02.56]A match.What do you do? [01:07.89]1.Put the candle in the candleholder. [01:14.14]2.Put the candle- holder in the dish [01:20.38]3.Fill the dish half full of water. [01:26.86]4.Light the candle. [01:31.61]5.Let the candle burn for two or three minutes. [01:39.47]6.Carefully put the jar over the candle. [01:46.74]7.Look at the water in the jar.What observation can you make? [01:56.72]What is happening? [02:00.06]As the candle burns,it uses up oxygen in the air. [02:06.90]When the candle stops burning it has used up all the oxygen in the air. [02:16.05]The water inside the jar then rises. [02:22.11]How far did the water rise?Air is about one- fifth oxygen, [02:30.36]so the water rises and fills about one- fifth of the jar.

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