By Parke Brewer The women's pole vault provided one of the stirring dramas of the 2004 Olympic track and field competition. Until the mid 1990s, women's pole vault was not taken very seriously, mainly

发表于:2018-12-12 / 阅读(49) / 评论(0) 分类 VOA2004(下)--雅典奥运

Larry Newitt from the Geological Survey of Canada charts the movement of the magnetic North Pole as it wanders the icy reaches of northern Canada. To determine where the magnetic pole / is, we can't rely on one single observation. What I try to do is

发表于:2019-01-22 / 阅读(51) / 评论(0) 分类 自然百科2011年