单项选择题

During Mir’s lifetime, Russia spent about US $4.2 billion to build and maintain the station.
The Soviet Union launched Mir, which was designed to last from three to five years, on February 20,1986, and housed 104 astronauts over 12 years and seven months, most of whom were not Russian. In fact, it became the first intemational space station by playing host to 62 people from 11 countries. From 1995 through 1998, seven astronauts from the United States took turns living on Mir for up to six months each. They were among the 37 Americans who visited the station during nine stopovers by space shuffles.
______ Americans ever visited Mir during its lifetime.

A. 62
B. 37
C. 11
D. Seven
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单项选择题
In addition to his theory of color, Newton developed a theory of how light travels. This is known as the corpuscular theory of light, meaning that light travels as a series of tiny bits rather than in continuing waves. Newton sent his writings to the Royal Society where they were given to a committee led by Hooke. Since the corpuscular theory was different from his own theory, Hooke attacked the paper. Soon others started to argue, and Hooke was supported by a scientist from Holland, Chritain Huygens. At one time, Newton was so unhappy with the whole affair that he decided never again to publish any of his work. The bitter argument continued over the years that followed. At first, Hooke and Huygens received most of the support. Later, after Newton had changed his mind and let his work on gravity be published, he became so famous that things changed. Now people believed Newton could do nothing wrong, and for a hundred years they followed his theory. Then, in the early part of the 19th century, the experiments of a French scientist, Augustin Fresnel, showed that light could be explained best by a wave theory. So the scientists changed sides again, saying that Newton’s ideas had delayed scientific progress for a hundred years. Newton’s publishing ofhis work on gravity resulted in that
A. Newton became the best known scientist.
B. his corpuscular theory of light was accepted.
C. scientists would believe in Newton only.
D. most people have supposed Newton till now.