in the sky与on the sky的区别

in the sky是空中的意思
给你几个例句
There are countless stars in the sky.
天上有无数的星星.
There are many swallows flying in the sky.
天空中有许多燕子.
He stared up at the stars twinkling in the sky above him.
他抬眼凝视着头顶上方星光闪烁的天空.
A cloud is a mass of vapour in the sky.
云是天空中的水汽团.
on the sky 没有这么一说的,是个错误的短语.OVER