The earth was just【小题1】cloud of dust after the “Big Bang”. The earth exploded loudly with fire and rock. 【小题2】were in time to produce many things，which were to make the earth’s atmosphere. As the earth cooled down，water began to appear on【小题3】surface. It allowed the earth to dissolve【小题4】gases. Then life began to develop.

Small plants multiplied and filled the first oceans and seas with oxygen. This encouraged the development of early shellfish and fish. Land animals such【小题5】insects，reptiles and dinosaurs appeared after green plants appeared. Small clever animals spread all【小题6】the earth. They【小题7】 putting too much carbon dioxide into the atmosphere, which prevents heat from 【小题8】from the earth into space.Whether life will continue on the earth for millions of years to come will depend【小题9】whether this problem 【小题10】be solved．