The dog has always been considered man a best friend. Always noted for being part

The dog has always been considered man" a best friend. Always noted for being particularly faithful in watching over children, he also has his place by fireside, in the cow pasture, on the sheep range, and beside the hunter in forest or blind. He is easy to train, works hard, and often performs astonishing feats. And in the frozen polar regions he was once the principal motive power, before being largely displaced by the plane and helicopter

Because he howls or whines(哀鸣) in the presence of impending (即将发生的) death, the dog was once thought to have supernatural powers and believed to be capable of seeing gods and ghosts invisible to people. Actually, the basis for these beliefs lies in the dog"s sensitivity to people"s feelings and his superior hearing ability and sense of smell, which enable him to detect signs hidden from human observation. His record of saving lives is outstanding, for he often gives warning of fire and other dangers not noticed by his master

The dog, s major contribution, however, has been to medical research. Both his diet and his structure are comparable to those of the human being, and so he has been the su 灼 ect of countless demonstrations and experiments. Open-heart surgery has been made possible largely because of the dog. But his sacrifice has repaid his own species as well by safeguarding it from rabies (狂犬病) ,distemper, and other disease

26. The dog has always been noted for _______

A. protecting children B. assisting shepherds

C. helping hunters D herding a cattle

27. The dog is useful to herders because he is _________

A. loyal B. easily trained

C. hardworking D all of the above

28. The dog probably whines in the presence of death because he can ________

A. see ghosts and spirits

B. give warning of danger

C. sense unhappiness around him

D. perform. astonishing feats

29. The dog has been of most value to people in the development of____________

A a treatment for rabies B. open-heart surgery

C. a cure for distemper D all of the above

30. The article does not say whether the scientists" experiments with dog have

A. benefited animals other than dogs

B. served people

C. helped other dogs

D contributed to medical knowledge