题目内容：

    While every dog owner knows their dogs can read their moods perfectly, scientists have always been a little doubtful. Now thanks to some researchers at the University of Veterinary Medicine in Vienna, Austria, we finally have some convincing evidence.

For this study, biologist Corson Miller and his team exposed eleven selected dogs to digital images of women that were either angry or happy. Half the dogs were rewarded for touching the screen when shown a happy face, while the other half were given their treat for selecting those that appeared angry.

Interestingly, the dogs were not provided with the entire face. Some dogs were shown only upper halves while the others observed lower halves. That’s because the scientists believe humans show their eruptions on their entire face.

After some training on how to recognize small differences like the wrinkles between the eyes or the changes in their shape that accompany the happy or angry expressions, the dogs were mostly able to identify the correct expression not only on a familiar face but on a strange face, the researchers concluded the dogs were smart enough to read human emotions.

They also found those being trained to read angry expressions took a longer time to learn. They guess  it may be  because dogs  find angry  faces disgusting, causing  them to  back  away  quickly. However, once the smart dogs realized they were getting rewarded, the trepidation seemed to disappear. In fact, the dogs had such a good time playing the computer “game” that scientists had a hard time keeping them away from the touch screens after the study was completed.

The researchers also noticed only dogs with a male owner had a harder time understanding the expressions correctly. Since the touched screen models were all females, this confirmed what had been observed in previous studies—dogs are more efficient at reading facial expressions of people that are the same gender as their owner.

1.How did the scientists conduct the experiment?

A.By mixing the selected dogs together.

B.By rewarding only half of the dogs touching the screen.

C.By leaving dogs to women who are either happy or angry.

D.By showing digital pictures of women’s happy or angry faces.

2.What is the meaning of the underlined word “trepidation” in Paragraph 5?

A.fear and hesitation B.doubt and uncertainty

C.curiosity and eagerness D.excitement and happiness

3.According to the last paragraph, dogs with female owners ________.

A.are scared away at the male faces

B.can only read the expressions on partial faces

C.are uninterested in telling facial expressions

D.have difficulty telling the moods on the faces of males

4.What is the best title for this passage?

A.Dogs and Their Owners B.Dogs’ Mood Research

C.Dogs Identify the Moods D.Mood Changes Influence Dogs