题目

短周期主族元素W、X、Y、Z的原子序数依次增大，W、X原子的最外层电子数之比为4∶3，Z原子比X原子的核外电子数多4。下列说法正确的是 A．W、Y、Z的电负性大小顺序一定是Z>Y>W B．W、X、Y、Z的原子半径大小顺序可能是W>X>Y>Z C．Y、Z形成的分子的空间构型可能是正四面体 D．WY2分子中σ键与π键的数目之比是2∶1Since the mid-1980's, growing numbers of Asians  ______ in New Zeahnd, and they _____about six percent of the total population. A. had settled; are made up of    B. have settled; make up  C. settled; make up of   　　　　D. are settling; make up for