题目

 Shelly had prepared carefully for her biology examination so that she could be sure of passing it at her first_________.        A. intention                 B. attempt                   C. purpose           D. desire 答案：B地壳中含量位于第一、二位的元素之间形成的化合物不具有的性质是(　　)A.常温下能与苛性钠反应B.常温下能与水反应C.常温下能与氢氟酸反应D.高温时能与氧化钙反应