题目内容：

My young cousin Jim seems to have endless question to ask every day. One day, he asked me what life on earth began after watching a film. To be honest, the question remains a puzzle to me. Besides, in order not to let him down, I found the answer in a book, said, “Long ago the earth was a cloud dust. The dust settled into a solid globe before billions of years. The earth became so violently that it was not clear that the shape would last or not. It exploded loudly with fire and rock. Then water began to appear. As the time went on, different life forms began.”