八年级英语下册module-3Unit-2.pptVIP

yet 用于否定句和疑问句，意思是“还，尚”。not … yet 的意思是“还没，尚未”，表示某事物在某一时间尚未发生，但未来也许会发生。例如： I haven’t learnt any farther information yet. 我还没有得到进一步的信息。 Have you received her letter yet? 你收到她的来信了吗？ 3. The Earth is a planet and it goes around the sun. Seven other planets also go around the sun. 地球是颗行星，它围绕着太阳转。此外 还有七颗行星也围绕着太阳转。 太阳系的其他七颗行星：水星(Mercury)、金星(Venus)、火星(Mars)、木星(Jupiter)、土星(Saturn)、天王星(Uranus)、海王星(Neptune)。 4. None of them has an environment like that of the earth, so scientists do not think they will find life on them. 他们中没有一个有像地球这样的环境，因 此科学家们认为在他们上面找不到生命。 none of … 表示（三个以上）一个也没 有。做主语时，谓语动词可用单数或复 数。 * * earth moon spaceship astronaut space travel Scientists have sent spaceship to Mars. The journey has taken several months. Astronauts have already been to the moon. No one has been to Mars yet, because Mars is very far away, much farther than the moon. Lots of scientists are working hard in order to send astronauts to Mars one day. Scientists think that there has been life on the Earth for hundreds of millions of years. However, we have not found life on any other plants yet. The Earth is a plant and it goes around the sun. Seven other planets also go around the sun. None of them has an environment like that of the earth, so scientists do not think they will find life on them. The sun and its planets are called the solar system, and our solar system is a small part of a much larger group of stars and planets, called the Galaxy or the Milky Way. There are billions of stars in the Galaxy, and our sun is only one of them. Scientists have also discovered many other galaxies in the universe. They are very far away and their light has to travel for many years to reach us. So how large is the universe? It is impossible to imagine. Scientists have sent spaceship to the planet Mars to take photos. They have even sent spaceships to travel outside the solar system. However, no spaceship has travelled far enough to reach other stars in our Galaxy. Look at the pictur