①曲线C过点（﹣1，1）；
②曲线C关于点（﹣1，1）成中心对称；
③若点P在曲线C上，点A、B分别在直线l1、l2上，则|PA|+|PB|不小于2k；
④设P0为曲线C上任意一点，则点P0关于直线l1：x=﹣1，点（﹣1，1）及直线f（x）对称的点分别为P1、P2、P3，则四边形P0P1P2P3的面积为定值4k2；其中，
所有正确结论的序号是____．
____
关于地球自转和公转的叙述，正确的是（ ）
下列四个图例中，表示铁路的符号是（ ）
Excuse ____ (I), is this your eraser?
A: What's the matter with you, young man?B: Oh, doctor. I'm not feeling well. ____ I think I will die.A: Die? I don't think so. Take it easy.（放轻松）____ B: Ahh... I must have a terrible illness.A: Em...____ I am sure you will be all right soon.B: But I really feel very terrible. What should I do now?A: ____ B: Is that all?A: You should drink more water and you shouldn't eat spicy（辣的）food.B:____ A: No, you needn't
