The doctor thinks he will pull now. His temperature has gone down. A. together B. through C. over D. around 答案:B给出以下结论:①?a、b∈R,方程ax+b=0恰有一个解;②q∨p为真命题是“p∧q”为真命题的必要条件;③命题“a、b都是偶数,则a+b是偶数”的逆否命题是“a+b不是偶数,则a、b都不是偶数”.④命题p:?x0∈R,sinx0≤1,则¬p为?x∈R,sinx>1.其中正确结论的序号是②④②④.