A:16,32,46,60
B:16,30,42,56
C:16,28,40,52
D:16,30,58,72
下表为元素周期表中某一周期元素的原子结构示意图。请回答下列问题: (1)表中磷原子的核电荷数X=____;(2)表中具有相对稳定结构的元素是 ____ ; (3)在化学反应中,每个铝原子失去____个电子形成铝离子; (4)表中元素在周期表中处于第____ 周期,它们属于同一周期的原因是____
仙人掌的叶适应沙漠干旱生活逐渐变为刺状.这是( )
—I won't get good grades_______ I study hard.
—That's ______ everyone is trying his best to prepare for the exam.