宇宙中两个相距较近的星球可以看成双星，它们只在相互间的万有引力作用下，绕两球连线上的某一固定点做周期相同的匀速圆周运动．根据宇宙大爆炸理论，双星间的距离在不断缓慢增加，设双星仍做匀速圆周运动，则下列说法正确的是（   ）

如图所示，△ABC中，DE∥BC，若$\frac{AD}{DB}=\frac{1}{2}$则下列结论中错误的是（　　）

____以北的纬度叫北纬，____以南的纬度叫南纬，南北纬各____度。

A: Betty, will we study at school in the future?

B: ____ But we don't use paper, pens or rulers.

A: What will we use?

B: ____

A: But will we use pencils in the art class?

B: ____ We will draw pictures on the computers.

A: ____ How long will we study at school every day?

B: I think we will study for about three hours and then we can play games.

A: Really?

B: ____ It's just my dream.

A: It's my dream too.