Go ahead，talk to your dog. As many a dog owner will prove, our furry friends are listenin

Go ahead，talk to your dog.
As many a dog owner will prove, our furry friends are listening. Now, for the doubters, there is scientific proof that they understand much of what they hear. A border collie called Rico can fetch at least 200 objects by name， researchers in Germany say. The dog also appears to learn words for new objects as easily as a 3-year-old child would. Its word-learning skill is as good as that of a parrot or chimpanzee.
In one experiment, the researchers took all 200 items that Rico is supposed to know and divided them randomly into 20 sets of 10 objects each. The dog waited with one of his owners in one room, while an experimenter put a set of 10 objects into another room. Then, the owner told the dog to fetch one of the items. The dog had to go to the other room and bring the object back.
In four trials, Rico got 37 out of 40 mands right. Because the dog couldn't see anyone to get visual clues about what to bring back, the scientists concluded that he must understand the meanings of certain words.
In another experiment, the scientists took one toy that Rico had never seen before and put it in a room with seven toys whose names he already knew. The dog's owner then told him to fetch the object, using a word Rico had never heard.
In 7 out of 10 trials, Rico picked the right object, suggesting that he figured out the answer by process of elimination. A month later, he remembered half of the new names, which further impressed the researchers.
Rico is probably smarter than the average dog, the scientists say. For one thing, he's a border collie, a breed known for its mental abilities. In addition, the 9-year-old dog has been trained to retrieve toys by their names since he was 9 months old.
It's hard to know if all dogs understand at least some of the words we say. Even if they do, they can't talk back. Still, it wouldn't hurt to sweet-talk your pup every now and then. You might just get a big, wet kiss in return!
48．The passage is probably taken from a book on     
A．pets B．environment    C．culture     D．nutrition
49．It is implied that     
A．Rico is probably cleverer than the average dog
B．Only a few dogs can talk back to its owner
C．if a chimpanzee is trained ,it can also recognize the names of objects
D．All dogs can understand words
50．How long is it since Rico’s owner began to train him?
A．nine months  B．3years    C．over nine years      D．more than eight years
51．Rico can do all the following except     
A．understanding the meanings of certain words.
B．picking the right object by process of elimination
C．remembering all of the new names he learned    D．retrieving toys by their names48---51   ACDC