题目

下列各组物质的化学式、名称（或俗名）和分类三者不相等的是（   ） A．CaO、生石灰、氧化物                    B．CH4、甲烷、有机物 C．Na2CO3、纯碱、碱                       D．Ca(OH)2、氢氧化钙、碱 答案：C--- Do you mind telling us something about this area?--- Not at all. ________ of the land in this area _________ covered with trees and grass.A．Two fifth, isB．Two fifth, areC．Two fifths, isD．Two fifths, are