放在水平地面上的物体在20牛的水平拉力作用下移动了6米,当拉力消失后又移动了1米,求拉力所做的功。
Welcome to the 2012 London Olympic Games
Badminton
This sport was invented by British soldiers in India who called it Poono, the same name as the town in which they lived.
It was first played at the Olympics in 1992 at Barcelona. Although the rules of the modern sport were developed in England, Asian countries are now the best.
Football
There are two medal competitions for Olympic football, one for men's teams and one for women's.
Football was first played at the 1908 Olympic Games and it has been played at every Olympic Games ever since, except for Los Angeles 1932.
Archery
Archery has a 10,000-year history, when bows and arrows were first used in hunting and war.
Archery first appeared at the Paris Olympics of 1990.
Taekwondo
This Taekwondo sport's name means “the way of the hand and foot”. The players get points by hitting each other with these two parts of the body only. The players mustn't lie on the floor and no equipment can be used taekwondo first appeared at the 2000 Sydney Games.
改错。选出并改正。
Help yourself to some bread, children.
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神舟八号于2011年11月1日5时58分由改进型“长征二号”火箭顺利发射升空,此次火箭的起飞质量为497000公斤,数字497000用科学记数法可以表示为 ( )
【环境保护】工厂、矿山、垃圾填埋场等由于化学物质的排放和泄漏对环境进而对人体健康造成的危害越来越受到各国的重视,污染场地健康风险评价的重要性日益凸现。常州某厂生产过程中大量使用易挥发的有机溶剂,下图为该厂污染造成的人群健康风险评价模式图。
注:污染羽是指污染物随地下水移动从污染源向周边移动和扩散时所形成的污染区域。
指出工厂土壤污染造成人群健康风险的途径并提出防治对策。
真人秀父子互动节目“爸爸去哪儿”将组织5对父子(女)利用暑期到东海某无人海岛进行拍摄活动。摄制组在图中甲乙丙丁设置了四个钓鱼点,要求除了一位爸爸带孩子们抓螃蟹外,另外四个爸爸分别去四地钓鱼,约定一旦日落立即返回营地。下图为该岛等高线地形图,拍摄开始前,摄制组先要准备好露营地,图中最适合露营地的是( )