Ⅰ.语法填空
After the “Big Bang”， the earth was just a cloud of dust. Then the dust settled into a solid globe. The earth became __1__ (violence). Then it exploded loudly. In time, the water vapour was produced, __2__ (make) the earth's atmosphere cool down. Water then appeared on the surface. Many millions of years later, the small plants began developing in the water. They multiplied and filled the oceans and seas __3__ oxygen. And then green plants came into __4__. Later the plants grew into forests, and reptiles appeared on the land. They produced young generally by __5__(lay) eggs.
__6__ dinosaurs disappeared, mammals became more important. Small clever animals with hands and feet appeared all over the earth. __7__ time went by, they covered the earth and they are putting too much carbon dioxide into the atmosphere, __8__ prevents heat __9__ escaping from the earth into space. In the end the earth may become __10__ hot to live on.
