题目

 ______ the economic crisis getting more and more serious, the government is searching for ways to improve people’s life.     A. As                             B. With                       C. When                   D. If 答案：B   现有Na、C、Cl、O、H五种元素，从里面选择一种或几种元素组成物质，用化学式回答：①炼钢的气体                  ②炼铁的气体             ③洗涤剂    ④人的胃液中所含有的酸    ⑤火碱                 ⑥最简有机物    ．