A:Milk is cheaper than coke.
B:Milk is the most expensive.
C:Orange juice has the same price as water.
D:Coke is more expensive than orange juice.
呼吸系统的主要器官是( )
x=( )
如图所示,F为凸透镜L的焦点,OO′为凸透镜的主光轴,AB为射向凸透镜且过焦点的光线,在凸透镜的右侧有一平面镜MN和主光轴OO′成45°,请画出经凸透镜折射后和经平面镜反射后的完整光路图.