问题 选择题

太空授课中,王亚平成功地制成了晶莹剔透的大水球,并用注射器在水球中注入了红色的液体,最终看到了红色液体充满了整个水球。有关这个现象,下列说法错误的是

A.大水球处于完全失重状态

B.大水球处于平衡状态 

C.大水球成球形是因为水的表面张力 

D.红色液体的扩散反映了液体分子的无规则运动

答案

答案:B

题目分析:该大水球的重力完全充当向心力,处于完全失重状态,A正确B错误;表面张力是使表面收缩的力。在没有外力作用下,球形的表面积最小,即表面收缩得最小,故液滴为球形,C正确;红色液体在水球中慢慢散开,这是一种扩散现象,说明分子在不停的做无规则运动,D正确;

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"We’re using the wrong word," says Sean Drysdale, a desperate doctor from a rural hospital at Hlabisa in northern KwaZulu-Natal. "This isn’t an epidemic, it’s a disaster. " A recent UNIEF report, which states that almost one-third of Swaziland’s 900,000 people are infected with HIV, the virus that causes AIDS, supports this diagnosis. HIV is spreading faster in southern Africa than anywhere else in the world.

But is anyone paying attention Despite the fact that most of the world’s 33.5 million HIV/AIDS cases are in sub-Saharan Africa—with an additional 4 million infected each year—the priorities at last week’s Organization of African Unity summit were conflict resolution and economies development. Yet the epidemic could have a greater effect on economic development—or, rather, the lack of it—than many politicians suspect.

While business leaders are more concerned about the 2K millennium bug than the long-term effect of AIDS, statistics show that the workfare in South Africa, for instance, is likely to be 20% HIV positive by next year. Medical officials and researchers warn that not a single country in the region has a cohesive government strategy to tackle the crisis.

The way managers address AIDS in the workplace will determine whether their companies survive the first decade of the 21st century, says Deane Moore, an actuary for South Africa’s Metropolitan Life Insurance Company. Moore estimates that in South Africa there will be 580,000 new AIDS cases a year and a life expectancy of just 38 by 2010. "We’ll be back to the Middle Ages," says Drysdale, whose hospital is in one of the areas in South Africa with the highest rates of HIV infection. "The graph is heading toward the vertical. And yet people are still not taking it seriously. "

Most southern African countries are simply too poor to supply more than basic health services, let alone medicines, to confront the crisis. Patients in some government hospitals in Harare have to supply their own bedding, food, drugs and, in some cases, even their own nurses. Zimbabwe’s frail domestic economy depends to a large extent on informal enterprises and small businesses, many of which are going bankrupt as AIDS takes its toll on owners and employees. "The ripple effect is devastating," says Harare AIDS researcher Rene Loewenson.

More ominous are the implications for South Africa with a sophisticated industrial infrastructure as well as a widespread informal sector. While the South African government is active in promoting AIDS education, it hasn’t the money, manpower or material to cope with the attack of AIDS.

Which is the major reason for the AIDS situation in South Africa()

A. The poor economic power in the African countries

B. The industrial infrastructure is complex

C. The informal sector is widespread

D. The lack of government concern