A dog’s tail can tell you a lot more than you might think. Is it wagging (摇) to the left or is it wagging to the right?
“The direction of tail wagging does in fact matter，”said Giorgio Vallortigara，a professor at the University of Trento in Italy. Professor Vallortigara finds that the way the tail is wagging can tell you a lot about a dog’s state of mind—whether you’re a human or another dog.
What’s the difference between a left wag and a right wag？Professor Vallortigara and his colleagues have studied 43 dogs of various breeds — German Shepherds，Beagles，Boxers，Border Collies and some mutts. They find that if a dog wags its tail to the left. it’s feeling anxious or nervous. The reason could be an unfamiliar or dangerous situation，an unfamiliar person，or an unfamiliar and possibly threatening dog. But if the tail is wagging to the right，it means the dog is feeling relaxed and approachable.
“The tail is a very important signal，”said Thomas Reimchen，a biologist at the University of Victoria in British Columbia, Canada. ”There is a lot of visual information that dogs use when communicating with each other. ”
How did the scientists figure all this information out? They had the dogs in their study watch videotapes of other dogs. When the dog on the tape wagged its tail to the right，they say the other dogs remained calm and cool. But when the dog on the tape wagged its tail to the left，the other dogs got anxious.
The researchers are still not exactly sure if the direction of tail wagging is something the dog does consciously. They suspect that it might be something the dog does without even thinking about it — kind of like when you get goose bumps if something scares or startles you. They plan to do more research to get more information about what dogs are thinking and feeling while they’re wagging. As Reimchen said，“I'm not going to be surprised if we find all sorts of really interesting processes that nobody has ever seen before. ”
Professor Vallortigara’s study focused on the relationship between_________.

A．a dog’s state of mind and its owner's feeling

B．a dog’s state of mind and the direction of its tail wagging

C．a dog’s sense of direction and its state of mind

D．a dog’s intention of tail wagging and its feeling

According to the study，dogs which wag their tails to the left may feel_________.

A．calm

B．happy

C．angry

D．nervous

It is implied in Thomas Reimchen’s words in Paragraph 4 that___________.

A．dogs’ tails play all important role in their growth

B．dogs show their feelings only by wagging their tails

C．dogs get to know others by watching tail wagging

D．dogs can understand each other by repeating tail wagging

How does the passage mainly develop?

A．By asking and analyzing questions

B．By making comparisons

C．By following the order of time

D．By providing examples