Ray and I like bird watching, but he enjoys it more that I
This question is rather vague, but there are many different things you can learn about Earth's history though the study of animals. For example: you can look at the fossils of dinosaurs and learn how they lived, their size, what era they were from, etc. If you are looking at live animals, you can determine how they live with the environment around them.
You use a comma if the dependen clause comes first
He aimed to puzzel the reader. He did this so that he could draw the reader in. Starting off by denying that you are mad, the first thing you want to know is why someone is accusing them of being "mad". So. it makes the reader continue reading.
Answer:
1. preview the main points
2. reinforce the central idea
