①After Pluto(冥王星)was found in 1930,people took it as the ninth planet in our solar system(太阳系).But it isn't like other planets.It is smaller and has a strange orbit(轨道).On August 24,scientists said,“Pluto is not a plane.”
About 2,500 scientists met in Prague.At first,some of them said that there would be 12 planets in our solar system.In the end,the scientists said that only Mercury,Venus,Earth,Mars Jupiter,Saturn,Uranus and Neptune are the planets in the solar system.②Each of these planets has its own orbit,and each of the planets is big enough to be a planet.Pluto's orbit overlaps(交叠)Neptune's and it is smaller than the other planets.③So Pluto is classified(分类)as a dwarf planet(矮行星),but no longer a planet in the solar system.
Students at school will have new schoolbooks to learn the new solar system!
l.根据①处完成下面的句子。(每空一词)
Before people ________ Pluto in 1930,there were ________ planets in our solar system.
2.根据②处完成下面的句子。(每空一词)
Every planet not only has its own ________,but also is ________ enough.