题目

—Where did the scholarship of last term you had got go, Annie? —On a computer,_________  on the desk over there. A．this              B． it            C．the one      D． one 答案：C下图是人体不可缺少的钙元素的原子结构示意图，则钙原子的A.质子数为20B.电子层数为3C.最外层电子数为10D.核外电子数为40