题目

原子核外电子排布式为[Ar] 3d54s2的元素是（    ） A. Cr         B.ds 区元素     C.ⅡA族元素       D. ⅦB族元素 答案：D I’ve won a holiday for two weeks to Florida, so I _____very soon.A．am leavingB．have leftC．leaveD．will have left