水平抛出的小球,t秒末的速度方向与水平方向的夹角为θ1,t+t0秒末速度方向与水

题型:选择题

问题:

水平抛出的小球,t秒末的速度方向与水平方向的夹角为θ1t+t0秒末速度方向与水平方向的夹角为θ2,忽略空气阻力,则小球初速度的大小为                             (   )

A.gt0(cosθ1-cosθ2)

B.

C.gt0(tanθ1-tanθ2)

D.

考点:平抛运动
题型:选择题

患者,男性,57岁,嗜烟约35年。慢性咳嗽咳痰10余年,进行性气促加重2年,被诊断为慢性支气管炎、阻塞性肺气肿,其X线胸片不会出现下列哪项?()

A.早期正常无明显变化,中、晚期可见肺纹理增加、粗乱

B.合并感染时有支气管周围炎症改变

C.合并感染时有支气管柱状扩张,肺纹理蜂窝状改变

D.肺容量增大,肋间隙增宽,膈肌低平

E.心脏悬垂并狭长

题型:选择题

中国证监会只能定期对证券经营机构从事投资银行业务的情况进行现场或者非现场的检查。()

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In her new book, “The Smartest Kids in the World,” Amanda Ripley, an investigative journalist, tells the story of Tom, a high-school student from Gettysburg, Pennsylvania, who decides to spend his senior year in Wroclaw, Poland. Poland is a surprising educational success story: in the past decade, the country raised students’ test scores from significantly below average to well above it. Polish kids have now outscored American kids in math and science, even though Poland spends, on average, less than half as much per student as the United States does. One of the most striking differences between the high school Tom attended in Gettysburg and the one he ends up at in Wroclaw is that the latter has no football team, or, for that matter, teams of any kind.

That American high schools lavish more time and money on sports than on math is an old complaint. This is not a matter of how any given student who plays sports does in school, but of the culture and its priorities. This December, when the latest Program for International Student Assessment(PISA) results are announced, it’s safe to predict that American high-school students will once again display their limited skills in math and reading, outscored not just by students in Poland but also by students in places like South Korea, Belgium, the Netherlands, Finland, Singapore, and Japan. Meanwhile, they will have played some very exciting football games, which will have been breathlessly written up in their hometown papers.

Why does this situation continue? Well, for one thing, kids like it. And for another, according to Ripley, parents seem to like the arrangement, too. She describes a tour she took of a school in Washington D.C., which costs thirty thousand dollars a year. The tour leader—a mother with three children in the school—was asked about the school’s flaws. When she said that the math program was weak, none of the parents taking the tour reacted. When she said that the football program was weak, the parents suddenly became concerned. “Really?” one of them asked worriedly, “What do you mean?”

One of the ironies of the situation is that sports reveal what is possible. American kids’ performance on the field shows just how well they can do when expectations are high. It’s too bad that their test scores show the same thing. 

小题1:Tom decides to spend his senior year in Poland because _______.

A.he intends to improve his scores

B.Polish kids are better at learning

C.sports are not supported at schools in Gettysburg

D.there are striking differences between the 2 countries小题2:According to Paragraph 2, we know that _______.

A.PISA plays a very important role in America

B.little time is spent on sports in Japanese schools

C.American high schools complain about sports time

D.too much importance is placed on sports in America小题3:The underlined sentence in the last paragraph means _______.

A.low expectations result in American students’ poor PISA performance

B.high expectations push up American students’ academic performance

C.American students’ academic performance worries their parents a lot

D.lacking practice contributes to American students’ average performance小题4:The purpose of this article is to _______.

A.compare Polish schools with those in America

B.call on American schools to learn from the Polish model

C.draw public attention to a weakness in American school tradition

D.explain what is wrong with American schools and provide solutions

题型:选择题

某一层材料的热阻R的大小取决于:

A.材料层的厚度
B.材料层的面积
C.材料的导热系数和材料层的厚度
D.材料的导热系数和材料层的面积

题型:选择题

喷他佐辛很少引起成瘾是因为()

A.拮抗μ受体

B.拮抗K受体

C.拮抗α受体

D.拮抗δ受体

E.拮抗K受体

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