题目

根据短文内容，从短文后的选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。Haveyou ever wondered how the trainers at Sea World get the 19,000­pound whale tojump 22 feet out of water and perform tricks? They get that whale to go over arope farther out of the water than most of us can imagine. .Sohow do the trainers at Sea World do it? The first thing they do is reinforce (强化) the behavior that they want repeated—in this case, to get thewhale to go over the rope. , in a position where the whale can'thelp but do what's expected of it. Every t设函数f（x）=-x2+4x在[m，n]上的值域是[-5，4]，则m+n的取值所组A.[0，6]B.[-1，1]C.[1，5]D.[1，7]