题目内容：

    Scientists can figure out a movie's emotional tone from the gasps(喘气) of its audience. These gases could point the way to a subtle(微妙的，精细的) form of human communication, a new study suggests.

"When you see a movie, you can hear the music and see the pictures. However, you don't realize here are chemical signals in the air. And they, too, could be affecting you, says Williams, who led the study. As an atmospheric chemist, he studies the chemical makeup of the air around us.

Williams started out measuring the air in a soccer stadium. He noticed that levels of carbon dioxide and other gases changed wildly whenever the crowd cheered. That got him wondering -- Could the gases people breathe out be influenced by emotions?

To find out, he went to the movies.

Williams and his coworkers measured air samples collected over six weeks in two movie theaters. Overall, 9,500 movie goers watched 16 films. They included a mix of comedy, romance, action and horror films. Among them were The Hunger Games, Catching Fire, Carrie, and Walking with Dinosaurs. The researchers gave scenes from the movies such labels as “suspense(悬疑)”, "laughter" and "crying". Then they looked for hundreds of chemicals in the air that showed up as people were watching particular movie scenes.

And certain scenes had distinct chemical "fingerprints". Scenes that had people laughing or on the edge of their seats were especially distinctive. During screenings of The Hunger Games, levels of carbon dioxide and isoprene got to the highest at two suspenseful moments. Because isoprene is related to muscle movement, the researchers think tense movie moments likely led to its spikes(尖峰). Williams and his colleagues think the increase in carbon dioxide was due to the viewers' increased pulse and breathing rates.

Scientists need more data to make stronger links between human emotions and what's in their breath. But Williams can see potential practical uses. Companies, for instance, could quickly measure the air during tests to see how people feel about new products. He pictures future studies recording other body variables(变数) as well. These might include heart rate and body temperature, for instance. "It's something to find out."

1.What was Williams's purpose of the research?

A.To know more about the makeup of the air.

B.To find out how the air changes in a crowded stadium.

C.To study how greatly the movies influence people's emotion.

D.To see whether people's emotion affects the air they breathe out.

2.What do we know about the experiment?

A.Each participant watched about 16 films.

B.The movies were a mixture of comedy and romance.

C.The film scenes were labeled with three main features.

D.The samples were taken in two theaters over six weeks.

3.In which situation are people most emotional?

A.Romantic moments. B.Exciting situations.

C.Suspenseful situations. D.Horrible moments.

4.What can we infer from the last paragraph?

A.Human emotions are strongly related to the chemicals humans breathe out.

B.People's temperature will be measured when they' re watching movies.

C.Williams thinks more measures should be taken for practical uses.

D.Companies will spend much money testing their new product.