——Will you join us to play basketball on Saturday afternoon?

——________, but I promised to go swimming with Eric.

二战后初期，世界呈现出“不战不和”的“冷战”局面。“冷战”时代开始的标志是（    ）

在平面斜坐标系$xoy$中$\angle xoy={45}^{°}$,点$P$的斜坐标定义为:“若$\overrightarrow{OP}=x_0\overrightarrow{e_1}+y_0\overrightarrow{e_2}$ (其中$\overrightarrow{e_1},\overrightarrow{e_2}$分别为与斜坐标系的$x$轴,$y$轴同方向的单位向量),则点$P$的坐标为$\left(x_0,y_0\right)$”.若$F_1\left(-1,0\right),F_2\left(1,0\right)$且动点$M\left(x,y\right)$满足$\left|\overrightarrow{M{F}_1}\right|=\left|\overrightarrow{M{F}_2}\right|$,则点$M$在斜坐标系中的轨迹方程为(  )