题目

The report is scheduled to be handed in tomorrow, so he ________ (attend)  the concert with his family yesterday. 答案：couldn't have attended 句意：这份报告定于明天提交，昨天他不可能和家人去听音乐会。couldn't have done表示对过去事情有把握的否定推测，意为“不可能已经做了某事”。求下列函数的值域：（1）y=2x+1,x∈{1，2，3，4，5}；（2）y=-x2-2x+3，-5≤x≤-2；（3）y=.