[单项选择]A. Once a week. B. Once a month.
C. Once a semester. D. Once a year.

[单项选择]American economists once spoofed university education as the only industry in which those who consume its product do not purchase it; those who produce it do not sell it, and those who finance it do not control it. That apt description, made in the 1970s, has been undermined since then by the emergence of the first for-profit universities in the United States. Controlled by entrepreneurs, these schools which number about 700 and counting sell a practical education to career-minded students and make a good buck doing it. They are now expanding abroad, creating the first multinational corporations in a sector long suspicious of balance sheets.
The companies are lured by a booming market in which capitalist competition is still scarce. The number of university students is expected to double in the next 25 years to 170 million worldwide. Demand greatly exceeds supply, because the 1990s saw massive global investment in primary and secondary schools, but not in universities. The number

[填空题]Jay Phelan once worked in MIT.

[填空题]

many once thought would be impossible to conduct on the internet. Some of the big American

[单项选择]People once widely believed that intelligent life existed on Mars. The 19th-century discovery of what appeared to be geometric designs cut across the surface was taken as evidence. The lines were thought to have been a system of canals that had been built to irrigate the surface. It is now clear that the "canals"—perhaps the most spectacular geologic features of Mars—are natural valleys where ancient rivers once flowed. Another fragmented idea concerns the planet’’s seasonal changes in color. Once attributed to the rapid spread of some life-form, these shifts are now known to develop from the movement of fine dust in the atmosphere. By the close of the 20th century none of the many experiments conducted by spacecraft had ever found persuasive evidence of life. Nevertheless, speculation continued over the existence of some form of life, in either the present or past. In 1996 scientists discovered organic compounds and minerals in a meteorite (陨石), consisting of Martian rock, t
A. Because the surface of Mars seemed to be geometric.
B. Because the lines were drawn across the surface of the planet.
C. Because a system of canals was thought to be there.
D. Because it was the Martians that built the canals.