问题 不定项选择

质量为m的小球被系在轻绳一端,在竖直平面内做半径为R的圆周运动,运动的过程中小球受到空气阻力的作用,设某一时刻小球通过轨道的最低点,此时绳子的张力为7mg,在此后小球继续做圆周运动,经过半个圆周恰好通过最高点,则在此过程中小球克服空气阻力所做的功是[ ]

A.

B.

C.

D.mgR

答案

答案:C

单项选择题 B1型题
阅读理解

阅读理解

      Harvard University named historian Drew Gilpin Faust as its first female president on Sunday, ending

a lengthy and secretive search to find a successor(接任者)to Lawrence Summers .

      The seven-member Harvard Corporation elected Faust, a noted scholar on History of the American

South and dean of Harvard's Radcliffe Institute for Advanced Study, as the university's 28th president.

      "This is a great day, and a historic day for Harvard." James R. Houghton, chairman of the presidential

search committee, said in a statement. "Drew Faust is an inspiring and accomplished leader, a superb

scholar, a dedicated(献身的) teacher, and a wonderful human being."

      Her selection is noteworthy given the heated debates over Summers' comments that genetic

differences between the sexes might help explain the lack of women in top science jobs.

      Faust has been dean of Radcliffe since 2001, two years after the former women's college was

combined into the university as a research center with a mission to study gender issues(性别问题).

      Some professors have quietly groused that the 371-year-old university is appointing a fifth president

who is not a scientist. No scientist has had the top job since James Bryant Conant retired in 1953; its last

four have come from the fields of classics, law, literature and economics.

      Faust is the first Harvard president who did not receive a degree from the university since Charles

Chauncy, a graduate of Cambridge University, who died in office in 1762. She attended the University

of Pennsylvania.

      "Teaching staff turned to her constantly," said Sheldon Hackney, a former president of the University

of Pennsylvania and historian who worked closely with Faust. "She's very clear. She has a sense of humor, but she's very strong-minded. You come to trust in her because she's so solid."    

1. Which might be the best title for the passage?

A. Harvard named its 1st female president.

B. History of Harvard University changed.

C. Debates on female equality ended.

D. Drew Gilpin Faust, a famous woman historian.

2. Lawrence Summers held the view that ________.

A. women cannot achieve as much as men in management

B. women cannot hold important positions in society

C. women can match men in science jobs

D. few women make top scientists owing to genes

3. The underlined word "groused" in the 6th paragraph means ________.

A. approved

B. commented

C. complained

D. indicated

4. This passage probably appears in a ________.

A. biography

B. personal letter

C. research paper    

D. newspaper