初中英语河北加拿大版学生用书25

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[00:00.00]和谐英语学习网 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.