题目

It’s really a pity that the heavy rain ______ to go for a picnic. A. made it impossible for us                           B. made that impossible for us C. made us impossible                                   D. made it impossible of us 答案：A 已知a>b>0，给出下列四个不等式：①a2>b2；②2a>2b－1；③>－； ④a3＋b3>2a2b. 其中一定成立的不等式为(　　) A．①②③                              B．①②④ C．①③④                              D．②③④