下列说法不正确的是（    ）

小明对中国地理位置的描述中，错误的是（　　）

观察下列等式： 1²=1,1²-2²=-3,  1²-2²+3²=6，1²-2²+3²-4²=-10  ，由以上等式推测出一个一般性的结论：

对于$n\in N^{*},1^2-2^2+3^2-4^2+..+(-1{)}^{n+1}{n}^2=$  ____.

两个相似三角形的面积比是9：16，则这两个三角形的相似比和周长的比分别为（　　）

从方框中选择恰当的句子，将对话补充完整。

A. Do you want it for your teacher?

B. How much is it?

C. Can I help you?

D. What is her favourite colour?

E. Can I look at that green one?

F. What about this one?

A: Good morning. ____

B: Yes, I'd like a birthday card.

A:____     

B: No, I'd like one for my mother.

As What a good daughter! ____

B: It looks nice. But my mother doesn't like red.

A:____

B: She likes blue and green.____

A: Of course. Here you are.

B: It's nice. It's my mother's favourite. ____

A: Two yuan, please.