Passage One
Animals perform many useful and entertaining jobs. Dogs are particularly valuable in guiding the blind, protecting property, finding lost people, and hunting down criminals. Horses are used in guarding herds; carrying men in lands where there are no roads, and helping farmers work their land. Pigeons have long been used to carry messages. Wild animals from the jungles, forests and seas are very popular performers in circuses and movies. People realize that, although animals may not have the same intelligence as human beings, they are smart enough to learn certain things.
The first thing a dog is taught is to obey. It should not take too long for him to learn commands. Simple orders, such as “sit”, “lie down”, “stay here”, and “come here”, can even be taught by a child.
Training a dog to be a watchdog often produces unexpected results. Some dogs quickly learn the difference between unwanted people and friends. This is because their masters welcome friends and invite them into their houses. However, some dogs will always attack the postman who comes to deliver letters. One explanation for this behavior is that, although the postman comes to the house often, he never enters the house. Therefore, the dog thinks the postman is someone who is not wanted, but keeps coming back anyway.
Masters of dogs who attack postmen can easily show the dog that the postman is a friend and that the dog does not need to treat him as an unwanted person. A dog is quite ready to do what his master wishes. And a dog is always happy when he is praised for understanding correctly.
Dogs can be taught to obey commands when the sound of a word is connected with a certain act. Two important factors in teaching a dog to obey commands are: using the same word each time for the same act, and teaching only one act at a time. Dogs can learn not only to sit, lie down, come, and stay in place when their masters go away, but also to jump, carry, and fetch.
After a dog learns to carry an object, he can learn to bring something back from a distance. A stick can be thrown far away and the dog enjoys running after it, and searching for it until he finds it. After a lot of practice, the dog then retrieves a stick (or other object) even when he has not seen it thrown. To teach a dog this skill, the master makes a simple trail by walking some distance in a straight line. Then he leaves the stick at the end of the trail. The dog learns to follow the straight line at first. Then, later, he learns to follow more irregular lines. Eventually, he can learn to follow an order instead of looking for an object. With this skill he can be very useful in tracking down lost people or criminals.
Some dogs attack the postman who comes to deliver mails because______.
A、their masters train them to do so
B、they don't like the behavior of the postman
C、they don't think he is a friend of their masters
D、the postman keeps coming and going all the time
【正确答案】：C
【题目解析】：根据Therefore, the dog thinks the postman is someone who is not wanted, but keeps coming back anyway.得知答案。
