Rockets in the Sky If someone asked you, What color is the sky? I expect that you would answer, Blue. I am afraid that you would be wrong. The sky has no color. When we see blue, we are looking at blue sunlight. The sunlight is shining on little bits of dust in the air. We know that there is air all around the world. We could not breathe without air. Airplanes could not fly without air. They need air to lift their wings. Airplanes cannot fly very high because as they go higher the air gets thinner. If we go far enough away from the earth, we find there is no air. What is the sky? The sky is space. In this space there is nothing except the sun, the moon and all the stars. Scientists have always wanted to know more about the other worlds in the space. They have looked at them through telescopes and in this way they have found out a great deal. The moon is about 384,000 kilometers away from the earth. An airplane cannot fly to the moon but there is a thing that can fly even when there is no air. This is rocket. I am sure that you are asking, How does a rocket fly? if you want to know, get a balloon and then blow it up until it is quite big. Do not tie up the neck o f the balloon. Let go! The balloon will fly off through the air very quickly. The air inside the balloon tries to get out. It rushes out through neck of the balloon and this pushes the balloon through the air. It does not need wings like an airplane. This is how a rocket works. It is not made of rubber like a balloon, of course. It is made of metal. The metal must not be heavy but it must be very strong. There is gas inside the rocket which is made very hot. When it rushes out of the end of the rocket, the rocket is pushed up into the air. Rockets can fly fat out into space. Rockets with men inside them have already reached the moon. Several rockets, without men inside them, have been sent to other worlds much farther away. One day rockets may be able to go anywhere in the space. 练习: 1. What color is the sky? A) It is blue. B) It is white. C) It is grey. D) It has no color. 2. When an airplane flies too high, A) the air will be too thin to support its wings. B) the air will become thicker. C) the air will exert pressure on it. D) the air will disappear in no time. 3. A rocket can fly to the moon because A) it looks like a balloon. B) it is much lighter than an airplane. C) it doesnt have wings. D) it works like an untied balloon. 4. Which of the following statements about a rocket is NOT true? A) It can fly when there is no air. B) It can fly without wings. C) It is made of strong metal. D) It is propelled by burning gas inside it. 5. A rocket is pushed up into the air when A) hot gas rushes out of its head. B) it is powered by gas. C) hot gas rushes out of its bottom. D) hot gas rushes out of its neck. Keys: DADDC
2013秋仁爱版八上《Topic 1 You should go to see a doctor》ppt课件2
仁爱八上 Unit 2 Topic1 Section C
仁爱版英语八年级第一单元动画素材
English is widely spoken around the world[上学期] 仁爱英语
仁爱八上 Unit 3 Topic1 Section B
仁爱八上 Unit 2 Topic1 Section B
仁爱八上 Unit 2 Topic 2 Section D
仁爱八上 Unit 2 Topic 2 Section B
仁爱八上 Unit 3 Topic1 Section D
八年级英语上学期 Unit 3 Topic 2 Section A仁爱英语
仁爱英语初二英语上学期Unit 1 Topic2
2013秋仁爱版八上《Topic 1 I love collecting stamps》ppt课件
2013秋仁爱版八上《Topic 1 I love collecting stamps》ppt课件1
2013秋仁爱版八上《Topic 1 You should go to see a doctor》ppt课件
仁爱八上Unit 1 Topic 1 Section D
仁爱版英语八上《Topic 3 What were you doing from seven to nine yesterday》ppt课件之三
仁爱八上 Unit 3 Topic 2 Section B
仁爱版八上《Topic 3 What should we do to fight SARS》ppt课件C
仁爱英语初二英语上学期unit 3
仁爱版八上《Topic 3 The students used live models, didn’t they》ppt课件
2013秋仁爱版八上《Topic 1 Plants and animals are important to us》ppt课件1
仁爱版英语八上《Topic 3 What were you doing from seven to nine yesterday》ppt课件之二
仁爱版八上《Unit 3 Our Hobbies》ppt复习课件
仁爱八上 Unit 3 Topic1 Section C
仁爱版八上《Unit 4 Our World》ppt复习课件
2013秋仁爱版八上《Topic 1 I love collecting stamps》ppt课件2
Unit 2 Topic2 SectionB仁爱版八年级上)
仁爱八上 Unit 3 Topic 2 Section C
仁爱八上 Unit 2 Topic 2 Section C
仁爱八上 Unit 2 Topic1 Section D
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |