According to the passage, a dog named Rico could______. [originaltext] Be car

Be careful what you say around your dog. It might understand more than you think. A dog named Rico recognizes the names of about 200 objects, say researchers in Germany.(1)The dog also appears to be able to learn new words as easily as a 3-year-old child. In one experiment, the researchers took all 200 items that Rico is supposed to know and divided them into 20 groups of 10 objects. Then the owner told the dog to go and fetch one of the items and bring it back. In four tests, Rico got 37 out of 40 commands right.(2)As the dog couldn’t see anyone to get clues, the scientists believe Rico 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 the dog already knew. The owner then told Rico to fetch the object, using a word the dog had never heard before.(3)The correct object was chosen in seven out of 10 tests, suggesting that the dog had worked out the answer by process of elimination. 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 dog every now and then. You might just get a big, wet kiss in return!