题目

The secret to living longer could be as simple as picking up your walking pace, according to a new study. Researchers from the University of Sydney found that walking at a brisk(快的) or fast pace was associated with a risk reduction of 24 percent for any cause of death.This effect was even more obvious in older age group, with fast walkers over the age of 60 reducing their risk of death by a surprising 53 percent. Professor Emmanuel Stamatakis, who led the study, explained, “A fast pace is generally five to six kilometers per hour, but it really depends on a walker’s fitness levels; an 读“美国农业带分布图”，完成下列各题。1.上图显示美国农业生产的突出特点是（ ）A.高度机械化 B.生产经营多样化C.地区生产专业化 D.农业生产商业化2.美国是世界上最大的农产品出口国，其发展农业生产的优势条件有（ ）①土壤肥沃，水源丰富 ②平原面积广，耕地多 ③地处热带，光热条件好 ④农业人口比例高，劳动力充足A. ①② B. ②③ C. ③④ D. ①③