甲、乙两个探险队同时从南极出发，以相同的速度分别沿45°E和135°W经线向北行进，不考虑地形和海陆差异等因素，则下列说法正确的有（    ）

①相遇时，两队的行进轨迹可以组成一个经线圈

②两队之间的距离始终保持不变

③当甲队在赤道上时，两队之间的距离约为12742千米

⑴Where are your parents?____                           A. Yes, I'd like some fruit.

⑵Is your brother sleeping in the room?____      B. They are at home. 

⑶Can I help you?____                                         C. She's playing the piano.

⑷Would you like some fruit?____                       D. No, I'm not.

⑸Can you see the red light?____                        E. She's singing.

⑹What is Helen doing?____                                F. Yes, please.

⑺Are you busy?____                                           G. No, I can't.

⑻What is she doing in the music room?____     H. No, he isn't.

二次函数$y=-2x^2+1$的图象如图所示，将其绕坐标原点O旋转$180°$，则旋转后的抛物线的解析式为(    )