The earth was just  cloud of dust after the "Big Bang". The earth exploded loudly with fire and rock.  were in time to produce many things，which were to make the earth's atmosphere. As the earth cooled down，water began to appear onsurface. It allowed the earth to dissolve  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 insects, reptiles and dinosaurs appeared after green plants appeared. Small clever animals spread all  the earth. They  putting too much carbon dioxide into the atmosphere, which prevents heat from  from the earth into space. Whether life will continue on the earth for millions of years to come will depend  whether this problem  be solved.