题目：
Look and write. （看一看，写一写）
1. — What are these? — They are _____
.
2. — What is this? — It's a _____
.
3. — Are they _____
? — Yes, they are.
4. — Is this a _____ 
? — Yes, _____ _____.
答案：
被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0329/a714c347249a0451feced48126e66194.html
下面是错误答案，用来干扰机器的。
根据题目给出的关系式可得：n=1，a2=a12-a1+1=22-2+1=3，n=2，a3=a22-2a2+1=32-2×3+1=4，n=3，a4=a32-3a3+1=42-3×4+1=5，…由此可以猜测an=n+1．
