in the sky 和 in the air的区别

in the sky 和 in the air的区别 in the sky or in the air? in the air 和on the air的区别是什么? in the sky与on the sky的区别 on the air 、in the air 、in the open air的区别 look up in the sky 和 look up into the sky 的区别 on the air和in the air的区别和用法 at the sky 与in the sky 区别 有没有in an open air,它 和in the open air有什么区别? it和that的区别The air in the countryside is much fresher than___ up in the sky HopeHope,In the sky.