题目

—Mummy, I would really like a laptop.—You get a laptop as long as you pass your entrance examination. 答案：【1】shall下列说法正确的是A. 第二周期元素的正化合价由+1→+7依次升高B. PH3在空气中可以自燃，根据元素周期律可以推知SiH4很难燃烧C. Cl的非金属性强于S，所以HClO3的酸性一定强于H2SO3D. Li的电子层数小于Al，但是Li的原子半径却却大于Al