题目

It is the first time that he ______ here and now it is high time that he ______ around.      A. come; should be shown                             B. has come; was shown                C. came; was shown                                    D. has come; be shown 答案：B已知 ①2C(s)+O2(g)===2CO（g）    △H=-221.0kJ·mol-1                    ②2H2(g)+O2(g)===2H2O（g）   △H= -483.6kJ·mol-1 则反应C(s)+H2O(g)===CO(g)+H2(g)的△H为                              （    ）     A．+131.3kJ·mol-1                   B．-131.3kJ·mol-1     C．-352.3kJ·mol-1                   D．+262.6kJ·mol-1