A. is a good example of increased salinity in freezing sea water B. is much larger in area than the Arctic oceans C. has a much lower salinity now than ever D. has the denser water in its upper parts 参考答案:A 答案解析:[定位] 最后一段第1句。 [解析] 选项A是对该句的同义改写。 [点睛] 同一句可知选项C错。选项B根本没有提及。文章最后一句表明D正好与事实相反。