题目

决定元素化学性质的主要因素是原子的                                （    ）A.核外电子数      B.最外层电子数  C.核电荷数        D.核内质子数与中子数之和 答案：BYou'd better check the train schedule______ .we have to take a train to Chengdu.A. even if B. as ifC. incase D. as long as