题目

已知1—18号元素的离子aW3+、bX+、cY2－、dZ－都具有相同的电子层结构，下列关系正确的是 A．质子数：c＞b                       B．离子的还原性：Y2－＞Z－ C．氢化物的稳定性：H2Y＞HZ           D．原子半径X＜W 答案：B The students are very busy because they have so ________ books to read and so ________ homework to do every day． [　　] A．many; many B．much; much C．many; much D．much; many