Scientists think that there has been life on earth for millions of years． However， we haven't found life on other planets yet． The earth is a planet and it goes around the sun． And there are seven other planets that also go around the sun． The sun and its planets are called the solar system． The solar system is a small part of the universe．

Scientists has launched many spaceships to explore other planets in the solar system． Some spaceships have gone beyond the solar system． However， no one has discovered any life in space yet．

Why has no one from other planets sent us a message？ Have they tried to send information to us？ With so many stars in space， are we alone， or is there life on other planets in space？

（1）Scientists think that there has been life on earth for 　　．

A．	millions years
B．	millions of years
C．	million years
D．	million of years

（2）The earth is a planet and it goes around 　　．

A．	the moon
B．	the solar system
C．	the sun
D．	the universe

（3）The solar system is a small part of 　　．

A．	the planets
B．	the universe
C．	the spaceship
D．	the earth

（4） 　　have gone beyond the solar system．

A．	Some explorers
B．	Some planets
C．	Some scientists
D．	Some spaceships

（5）What's the best title of the passage？ 　　

A．	Is There Life Out There？
B．	Our Planet
C．	The Stars at Night
D．	The Spaceship