Don't worry. Your package ____ (keep) here until you come back, so enjoy shopping here.
如图所示,空间有一水平匀强电场,在竖直平面内有一带电微粒以一定初速度沿图中虚直线由O运动至P,关于其能量变化情况的说法,正确的是( )
关于纬线的正确说法是( )