(·株洲二中高三第一次月考) 24. The boy wanted to ride his bicycle in the street, but his mother told him _____. A. not to B. couldn’t C. not do it D. do not to 答案:A我国是世界上严重缺水的国家之一,目前我国年可利用的淡水资源总量为27500亿m3,人均占有淡水资源量居全世界第110位,因此我们要节约用水.27500亿这个数用科学记数法表示(保留两个有效数字)为:______.