题干

滑轮组之所以有引入额外功是因为考虑到:________两个因素.
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摩擦,动滑轮重

同类题2

近代以来,中国经济经历了从小农经济向近代经济的转变。阅读下列材料:

材料一:精耕细作的密集型农业,传统技术发展到了极其完美的水平,中国的经济好像已陷入了一种“高水平平衡的陷阱”之中。西方的干预对中国经济体制的运转,产生了深刻的冲击。在过去,由于明清两代政府抑制贸易和航海事业,中国的经济变成了内向型的。在19世纪中期的战争和叛乱危机中,新活力的诸种因素正在聚集。1860年以后,对外贸易急剧增长,中国建立起它最初的现代企业。

——《剑桥中华民国史》

材料二:面对“三千年未有之大变局”,清政府开展了“自强”运动,……这场变革“仿效西法”,虽取得一时成就,但“徒袭人之皮毛,而未顾己之命脉”,“自强”的目的并没有达到。……“革命”后民族资本主义就开足了马力。但是这一城市经济和社会的巨大进步,更多地产生于第一次世界大战所造成的经济奇迹,而较少地受惠于一场早已被军人接管了的革命。在半殖民地的中国,资产阶级革命的逻辑受制于外部的国际关系的演变。

——《剑桥中华民国史》

材料三:著名的实业家宋裴卿1932年成立了“东亚毛呢纺织有限公司”,决心走实业救国之路。……1935年4月,筹建新厂,设备齐全,机器先进,使“东亚”成为天津民族工业中的佼佼者。1937年“七七”事变后,“东亚”在夹缝中挣扎了8年,多次陷于困境。到1948年,“东亚”已是奄奄一息了。

——《百年巨商》

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同类题5

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    When Steve Jobs was born on Febuary24,1955, in San Francisco , California, his unmarried mother decided to put him for adoption because she wanted a girl. So in the middle of the night, his mother called a lawyer named Paul Jobs and said, “We have an unexpected baby boy; do you want him?” But his mother told his future parents to promise that they would send Jobs to college. After Steve Jobs graduated from high school, he went to college but decided to drop out because it was so expensive that he had to sleep on the floor in his friends' rooms.

    At 20, he and a friend(Steve Wozniak) started a company in a garage on April 1, 1976. Jobs named their company ----Apple in memory of a happy summer he had spent as an orchard (果园) in Oregon.

    After 10 years of hard time and failures, starting from two kids working in a garage, Apple computer eventually grew into a big company with over 4000 employees.

    At 30, Jobs , however, was fired from the company he co-founded. But after he had to leave the company, Apple was under heavy pressure from rival (对手) Microsoft and in 1996 posted billions of dollars in losses. Apple needed Steve Jobs and he was appointed as Apple' CEO in1997. Under his leadership, Apple returned to profitability and introduced new products such as the iPhone and the iPod.

    Steve Jobs once said, “Sometimes life hits you in the head with a brick, Don't lose faith. I'm convinced that the only thing that kept me going was that I loved what I did. You've got to find what you love. If you haven't found it yet, keep looking.