Gail and her dog, Sam, are standing at the street corner. They're1 or the cars to go by. What do they want to do？They want to go2 the street. Sam will have to decide when they should cross.
Some blind people use special trained dogs3 them tell （级别） when and where they would go. But not every dog can do4 . A dog for the blind must be clever. The dog must be trained （被训练） at a special school. He is taught （被教会） to walk5 the trainer's legs. He is taught to walk6 his trainer does.
The blind person goes to the school, too. He trains with the dog. He holds the leather belt （皮带） around the dog's neck tightly （紧紧地）. 7 , he feels the movements （动作） and knows when and where to walk.
At the street corner, Sam8 read the traffic lights. It's not because he's careless. It's just because dogs can't tell red lights from green ones. He is trained to watch the cars, and tell what time is for him and Gail to cross.
Sam is9 to Gail. He does her seeing for her. He keeps her out of danger. So Sam is not only Gail's10 he's also her best friend.
