由于血缘关系的亲疏不同，西周贵族集团形成的宗法等级序列应该是（   ）

阅读理解
   The best thing about going to school is learning how to read. Books are great friends. They can help you to learn about anything you want to know. They can go anywhere with you. You can read about animals, faraway places, people, and anything else.
   Books are written by people called authors(作者). Authors think of things they want to write about. They make a plan for a book and start to write .Some authors write books that give us information(信息)and teach us things. Authors are very important people because they help us learn. Find a good book to read and read every day ,You will enjoy your time with a good book.