Read the passage carefully and choose the best answers.

1．Why was life able to develop on the earth but not on other planets?

A．Because the earth had a solid shape.

B．Because the earth did not have harmful gases in its atmosphere.

C．Because water stayed on the earth but not on other planets.

D．Because the earth was neither too hot nor too cold.

答案　C

2．Why was it necessary for plants to grow before animals?

A．Because animals needed plants to protect them from the sun.

B．Because plants provided oxygen for animals to breathe.

C．Because animals could hide from hunters in the forest.

D．Because it was easier for plants to grow.

答案　B

3．What is the correct order according to the passage?

①The clever animals with hands and feet appeared and spread all over the earth.

②The "Big Bang"．

③Small plants began to appear on the surface of the water.

④65 million years ago，the age of the dinosaurs ended.

A．②①③④ B．④③①②

C．②④③① D．②③④①

答案　D

4．Early humans appeared after dinosaurs died out million years later.

A．67.6 B．62.4 C．65 D．140

答案　B

5．What is the main idea of the text?

A．The formation of the earth.

B．The arrival of humans and their impact on the earth.

C．The development of plants and animals on the earth.

D．The origin of life on the earth.

答案　D

After understanding the passage，please fill in the following blanks.

The earth was just 1.a cloud of dust after the "Big Bang"．The earth exploded