⑴Is it on your bed? A. Because I am sad.
⑵Where's my bag? B. Because 7 ate 9.
⑶Why are you crying? C. Because it didn't want to be a hot dog.
⑷Why was 6 afraid of 7? D. No, it isn't.
⑸Why did the dog sit under the tree? E. It's under my bed.
(1)9个连续偶数的平均数是90,这些数中最小的一个是2,最大的是18.
(2)暗室里有红、绿、黄三种颜色的袜子若干只,为确保取出一双相同颜色的袜子,最少要取4只.
(3)某班共有学生48人,其中27人会游泳,25人会骑自行车,有12人既不会游泳也不会骑自行车,那么这个班既会游泳又会骑自行车的有16人.
(4)一个楼梯共有10级,如果每次能向上迈一级或两级,登上这10级楼梯,一共有89种不同的走法.