All the planets in the solar system go around the sun. There are eight planets in the solar system. Years ago, there were nine planets. Ever since Pluto (冥王星) was demoted (使降级), we’ve had just eight planets.
Some scientists have studied the farthest reaches（研究）of our solar system. They believe there might be another planet out there. They call it Planet Nine. What would Planet Nine be like? Scientists believe it could be about three times larger and ten times heavier than the earth.
If Planet Nine is out there, why haven’t we found it yet? Scientists are still reaching for it because it’s so far away. They believe it could take Planet Nine as long as 20,000 years to go around the Sun. Scientists also think Planet Nine could be as much as 10,000 times darker than Pluto.
It is very difficult to search for such a dark planet in the whole solar system. Could our solar system have a ninth planet? We hope to know the answer in the near future.
【小题1】From the first paragraph, we can know Pluto
.
| A．goes around the Earth |
| B．was a planet years ago |
| C．was not demoted |
【小题2】Scientists think Planet Nine may be
.
| A．three times larger than the sun |
| B．out of the solar system |
| C．ten times heavier than the earth |
【小题3】We haven’t found Planet Nine yet because
.
| A．it’s far and dark |
| B．it doesn’t go around the sun |
| C．it’s large and heavy |
【小题4】From the passage, we know that
.
| A．scientists are still reaching for Planet Nine |
| B．it is easy to search for such a dark planet |
| C．our solar system can’t have a ninth planet |
【小题5】Which of the following could be the best title for the passage?
| A．Solar System | B．Dark Pluto | C．Planet Nine |
