题目

Pleasant as they made it _________ in Yangzhou, we felt tired after the long journey.     A. to travel       B. travel        C. traveled      D. traveling   答案：A给出下列命题：①“x＞2”是“x≥2”的必要不充分条件；②“若x≠3，则x2-2x-3≠0”的逆否命题是假命题；③“9＜k＜15”是“方程x215-k+y2k-9=1表示椭圆”的充要条件．其中真命题的个数是______个．