3．Why have dogs been man's friends for thousands of years according to the passage？ A．Because dogs are brave to watch the door for their master． B．Because dogs have helped people in many ways． C．Because dogs have provided delicious meat for many people．
5．11．A．It's a blue bike． B．It's a green bike． C．It's a green toy train． 12．A．His mother． B．His father． C．He bought it for himself． 13．A．For five years． B．Since he was five． C．For four years． 14．A．Because it gave him sweet memories． B．Because he learned how to ride a bike on it． C．Because he went to school on it． 15．A．Old． B．Special． C．Common．
