如果一个正整数能表示为两个连续偶数的平方差,那么称这个正整数为“神秘数”,如:4=22-02,12=42-22,20=62-42,因此4,12,20这三个数都是神秘数. (1)28和2 012这两个数是神秘数吗?为什么? (2)设两个连续偶数为2k+2和2k(其中k取非负整数),由这两个连续偶数构造的神秘数是4的倍数吗?为什么? (3)两个连续奇数的平方差(取正数)是神秘数吗?为什么?句型转换(5%)
1.These are my grandparents. (变一般疑问句)
_______ these ______ grandparents?
2.Is this his picture? (作肯定回答)
_______, ______ is.
3.The tape player is in the room. (对划线部分提问)
_______ ________ the tape player?
4.She is a nice girl. (单数变复数)
_______ are nice ______.
5.They are erasers. (复数变单数)
______ is _____ eraser.