Your dog is as smart as any two year old, according to a new study. Dogs bring much happiness to their owners, and even improve human health. Most two year olds keep us busy in life—an important part of living a long and happy life. According to Stanley Coren, Ph. D. of the University of British Columbia, our dogs are smarter than we thought. Dr. Coren reviewed many studies to find out that dogs are as smart as 2 to 2. 5 year olds. Forget about one word orders—according to Coren, the smartest dogs can learn up to 250 words. Most dogs understand an average of 165 words. " The upper limit of dogs' ability to learn language is partly based on a study of a Border Collie(博得牧羊犬) named Rico who showed knowledge of 200 spoken words, and ' fast-track learning,' which scientists believed to be found only in humans and language-learning apes(猿). " Dogs are also great at tricking. During play, they have the ability to trick humans and other dogs in order to get treats. "And they are nearly as successful in tricking humans as humans are in tricking dogs," says Coren. Dogs can also count to four or five, which might explain how they know when their toys are missing. Coren explains, "Their astonishing flashes of smartness and creativity (创造力) are reminders that they may not be Einsteins, but are sure closer to humans than we thought. " Animals can do much to keep us happy, healthy, and protect us from harm. Stories of dog heroes can be found using a simple Internet search. Pets teach us sense of duty, keep us from loneliness, and can help with treatment of the disabled. Dogs are smarter than we thought—as smart as a two year old.

单选题 How do dogs bring happiness and health to humans according to the author?

单选题 What makes Rico special?

单选题 What does Dr. Coren say about a dog' s counting ability?

单选题 For someone interested in knowing more stories about dogs, the author suggests that he______.