For several billion years after the"Big Bang", ___ I ___ earthwas just a cloud of dust. Between 4. 5 and 3. 8 billion years agothe dust settled into a solid globe. The earth became so violentand it exploded ___ 2 __ (loud) with fire and rock. They were in ti me to produce many things, which were to make theearth's atmosphere. As the earth ___3 __ (cool) down, water beganto appear on its surface. The continued ___4___ (present ) allowed the earth __ _5_ dissolve harmful gases and acids intothe oceans and seas. This produced a chain reaction, which made ___6___ possible for life tothedevelop. Manymillions of years later ,th e first extremel y small plants multiplied and filled the oceans and seas __7___ oxygen. This encouraged the later development ofearly shellfish and all sorts of fish . L and animals such as insects , reptiles and dinosaurs and so on appear after green plants b egan to grow on lan d. Finally, some small clever animals, now with hand s and _8_ (foot) ,appeared and spread all over the earth. They are putting too muc h carbon dioxide into the atmosphere , ____ 9 ____ prevents heat from escaping from the earth into space. Whether life will continue on the earth for millions of years to come will depend on _10__ this problem can be solved.