阅读下面短文，按照句子结构的语法性和上下文连贯的要求，从各题所给的A、B、C和D项中选出最佳选项。As 1 experienced dog trainer, Du Linjia, 30, doesn't only "teach" dogs— he 2 lessons to dog owners, too. He has 10 years of experience, 3 he invites owners to train their dogs together with him to change dogs' behavior.
How does a trainer change a dog's behavior? "One common angry behavior of a dog is growling（低吼） at its owner to protect 4 food, " Du said, "In such cases, we need to know why. It may think that the owner is there to take its food, which we aim to change. "
By giving the dog more food while the owner is 5 getting closer, the dog begins to believe that it can be rewarded for letting humans come 6 . Problem can 7 .
Du believes that a dog trainer should be responsible. The trainer must never give up on 8 dog.
Understanding is important, too—a dog's worst behavior is usually 9 misleading actions by its owner. One needs to think 10 the dog's point of view. Du said a dog trainer needs to notice small changes in the dog's behavior 11 they can do what's needed in time.
"The future for dog trainers is promising, " Du said, adding that many customers are now learning how 12 their dogs' behaviors. Dog trainers need to have patience to help dogs overcome their 13 behaviors.
Du Linjia's method of training dogs involves both the dog and its owner, making it a more 14 method. The key to changing a dog's behavior is understanding 15 makes it to act in a certain way.
