题目

函数的图象为，①图象关于直线对称  ②函数在区间内是增函数； ③由的图象向右平移个单位长度可以得到图象。以上三个论断中，正确论断的是               。 答案：1,2   Jack ________ to Japan, for I met him in the bookstore just now.A.can't goB.couldn't goC.mustn't have goneD.can't have gone