在直角坐标系中，点A（3，-6）关于原点对称的点位于                      [ ]

A．第一象限    

B．第二象限    

C．第三象限    

D．第四象限

补全对话，每空一词。

A: Can I help you?

B: Yes, I   1   a shirt for my son.

A: What   2   does he like?

B: Blue.

A: What   3   this one?

B: Let me have a look.Oh! It's too   4   ,do you   5   a small one?

A: Yes, here you are.

B:    6       7   is it?

A: It's 80 dollars.

B: OK. I'll    8    it.Thanks.

A: You're welcome.