题干

如图,上下边界间距为l、方向水平向里的匀强磁场区域位于地面上方高l处.质量为m、边长为l、电阻为R的正方形线框距离磁场的上边界l处,沿水平方向抛出,线框的下边界进入磁场时加速度为零.则线框从抛出到触地的过程中(   )

A:沿水平方向的分运动始终是匀速运动

B:磁场的磁感应强度为 mgR2gl3

C:产生的电能为2mgl

D:运动时间为2 21g

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答案(点此获取答案解析)

A,C,D

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阅读理解

    It has been around for centuries, but up until very recently, traditional Chinese medicine (TCM) wasn't fully accepted abroad. The 2001 film Treatment(《刮痧》)tells the story of a Chinese man in the US who's charged with guasha, a form of TCM treatment, to cure his grandson's disease.

    During the last 10 years or so, however, TCM has been getting increasingly popular all over the world. A report says this style of health care, which includes different forms like herbal medicine and exercise, has spread to 183 countries and areas.

    "We have set up 10 TCM centers outside China, and all of them are popular among locals," said Wang Guoqiang at a news meeting on Dec 6. "Governments of 86 countries and areas have signed agreements with the Chinese government on TCM corporation(合作)."

    One of the reasons behind the growing popularity of TCM is the increase of scientific research into it. And after Tu Youyou-the Chinese scientist who discovered the anti-malaria(抗疟疾)drug qinghaosu(青蒿素)-won the Nobel Prize, TCM became even more famous all over the world.

    However, all these achievements in TCM don't mean that it's problem-free. Over the years,TCM has faced challenges in being able to prove that it has certain effects.

    Some researchers have suggested TCM should be more exact and work together with western medicine.

    "Bringing together with western medicine and TCM, rather than being in competition, is where the potential(潜力)for great effects is," said Bernhard Schwartlander,the China representative(代表)of the World Health Organization.