In the first one, Baker sat behind unknowing people in public places and stared at the backs of their heads for 5 to 15 minutes. The subjects（受试者）were eating, drinking, reading，studying, watching TV, or working at a computer. Baker made sure that the people could not tell that he was sitting behind them during those periods. Later, when he questioned the subjects, almost all of them said they had no sense that someone was staring at them. www.manfen6.com
For the second experiment, Baker told the subjects that they would be stared at from time to time from behind a two way mirror in a laboratory setting. The people had to write down when they felt they were being stared at and when they weren’t. Baker found that the subjects were no better at telling when they were stared at and when they weren’t .Baker found that the subjects were no better at telling when they were stared at than if they had just guessed.
Baker concludes that people do not have the ability to sense when they’re being stared at. If people doubt the outcome of his two experiments, said Baker, “I suggest they repeat the experiments and see for themselves.”
68. The purpose of the two experiments is to .
A. explain when people can have a sixth sense
B. show how people act while being watched in the lab
C. study whether humans can sense when they are stared at
D. prove why humans have a sixth sense
【实战演练练习十五】
阅读下面短代，并将代后标有A-F 的句子（或段落）插入代章中标号为71-75的合适位置，使短代结构完整。其中有一个句子（或段落）是多余的。
She is widely seen as proof that good looks can last forever. But, at nearly 500 years of age, time is catching up with the Mona Lisa.
71
“The thin, wooden panel on which the Mona Lisa is painted in oil has changed shape since experts checked it two years age,” the museum said. 72 .
73 “It is very interesting that when you’re not looking at her, she seems to be smiling, and then you look at her and she stops,” said Professor Margaret Livingstone of Harvard University, “It’s because direct vision is excellent at picking up detail, but less suited to looking at shadows. Da Vinci painted the smile in shadows.”
74 Da Vinci himself loved it so much that he always carried it with him, until it was eventually sold to France’s King Francis I in 1519.
In 1911, the painting was stolen from the Louvre by a former employee, who took it out of the museum hidden under his coat. He said he planned to return it to Italy. The painting was sent back to France two years later.
75
A. Nearly 6 million people go to see the Mona Lisa every year, many attracted by the mystery of her smile.
B. However, the actual history of the Mona Lisa is just as mysterious as the smile.
C. Visitors have notice the changes but repairing the world’s most famous painting is not easy. Experts are not sure about the materials the Italian artist used and their current chemical state.
D. The health of the famous picture, painted by Leonardo Da Vinci in 1905, is getting worse by the year, according to the Louvre Museum where it is housed.
E. The picture is now so valuable that no one can tell its exact price. Therefore, many thieves tried to steal it in any way they could think of.
F. During World War II, French did the painting in small towns to keep it out of the hands of German forces. Like many old ladies, the Mona Lisa has some interesting stories to tell.