①ax²+bx+c=0；②3（x﹣9）²﹣（x+1）²=1；③x+3= $\frac{1}{x}$ ；④（a²+1）x²﹣a=0；⑤ $\sqrt{x+1}$ =x﹣1，

其中一元二次方程的个数是（   ）

英国约翰•W•梅森在《冷战》一书中提出，如果把冷战时期重新定义为“长时期的和平”倒是颇为令人耳目一新的。文中作者对冷战重新定义的主要出发点是

五____四十

阅读下面的内容，并对后面的句子作出判断。

    It isn't a small shop(商店). It is near our home. It looks very lovely. My parents and I often go shopping. I buy books, rulers and pens in the shop. My parents buy milk , bread and eggs. The service(服务) is very good. We all like the shop.