题目

Paper produced every year is  _______________the world`s production of vehicles.     A.three times the weight         B.the three times weight        C.as three times heavy as        D.three times as heavier as 答案：A某元素的原子结构示意图如图所示，该元素的最低化合价为    ，该元素组成的单质在自来水生产过程中常做    ．