Scientists think that there has been life on Earth for millions of years. However, we haven’t found life on other planets yet. What not?

The Earth is a planet and it goes around the Sun. Seven other planets also go round the Sun. None of them has an environment with air, so people and things cannot grow. The Sun and its planets are called the solar system. The solar system（太阳系）is a small part of our galaxy.

The stars we see at night are the suns in other solar systems. There are more than 200 billion stars in our galaxy, called the Milky Way and our Sun is only one of them.

But scientists have discovered many other galaxies in universe. They are a long way away and their light has travelled for many years to reach us. It is hard to understand how large the universe is.

Scientists have sent lots of spacecraft to look at other planets in our solar system, and some spacecraft have gone beyond the solar system. However, no one has discovered any life in space yet.

But why has no one from other planets sent us a message? Have they tried to send information to us? With so many stars in the universe, are we alone, or is there life out there in space? We don’t know…yet.

【小题1】How long has there been life on Earth according to some scientists?

A．Millions of years.

B．Thousands of years.

C．Hundreds of years.

D．Billions of years.

【小题2】What is the solar system made up of?

A．The Earth and the Sun.	B．The Sun and its planets.
C．Milky Way and the Sun.	D．The Sun and other galaxies.

【小题3】What does the underlined word “discovered” mean in the passage?

A．Found.

B．Developed

C．Checked.

D．Explained.

【小题4】Which of the following is TRUE according to the passage?

A．The scientists have found life on other planets.

B．Many other galaxies are very far away from us.

C．Some planets in the solar system have an environment with air.

D．We know someone from other planets has sent us a message.

【小题5】In which part of a magazine can we read the passage?

A．Diet.

B．Fashion.

C．Science.

D．Culture.