题目内容：

Everyone knows that if a dog’s ears are up and its tail is wagging vigorously, it is definitely pleased to see you. but now scientists using a robot have found that the way dogs use their tails is more complicated than we thought, and that dogs which wag them to the left may he more friendly. The animal psychologists discovered that when real dogs approached a life-sized robot dog, they were less cautious about it when it was wagging its tail to the left, while if it was wagging its tail to the right, far fewer dogs approached it in a confident manner.

In the first experiments, 56 percent of the animals approached the model without hesitation when the tail was wagged to the left, while only 21 percent did so in the other situation. When the researchers excluded (排除) owners from being present, the result were: 31 percent of the dogs approached continuously when the tail was wagging to the left, while only 18 percent did so when it was on the right.

Animal psychologist Roger Mugford said it added to the growing evidence that does were even more complicated communicators than the animals more closely related to man such as monkeys. He said, “We know that dogs, in a sense, have languages, but it is more complicated because it is not just them wagging their tails, but also giving out chemical displays.”

He adds, “The research confirms earlier studies suggesting that dogs, like humans, had a left-side preference. If you are going to present a signal to a dog, it is sensible to put it on your left-hand side because that is where dogs, unlike most other animals, tend to look. It is another example of the similarity between dogs and humans. They are a lot more human than we give them credit for.”

1.What does it tell us if a dog wags its tail to the right?

A. It was very energetic    B. It was in a bad mood

C. It might be unfriendly    D. It must be confident

2.What can be inferred from the second paragraph?

A. Some dogs approach the robot dog confidently

B. Most dogs were afraid to approach the robot dog

C. Some dogs lack confidence with their owners present

D. Dog owners may influence the behaviour of their pets

3.What can we learn from animal psychologist’s experiments?

A. Dogs can communicate more than human beings

B. Dogs have more complicated emotions than monkeys

C. Dogs’ tail-wagging conveys more information than previously believed

D. Dogs’ intelligence can be much higher than any other kind of animal

4.What can we infer from Roger Mugfords words?

A. The Left-side preference should be studied further

B. Dogs have more in common with humans than we think

C. No other animals show the left-side preference except dogs

D. Dogs have a more complicated language than we people do