看窗外用英语可以表达为 "look out the window" 或 "look outside the window"。这种表达方式源于英语中两个动词短语："look out" 和 "look outside"。

"Look out" 意思是 "留心；注意"，它通常被用来提醒别人做某事。例如：

Look out! There's a car coming! (当心！有车来了！)

Look out for pickpockets when you're in the city. (在城市里时，要留心小偷。)

"Look outside" 意思是 "朝外看"，它通常被用来描述某人向外看的动作。例如：

I'm going to look outside and see if it's raining. (我要朝外看一看是否在下雨。)

She opened the window and looked outside. (她打开窗户，朝外看了看。)

由于 "look out" 和 "look outside" 都可以用来描述向外看的动作，所以 "look out the window" 和 "look outside the window" 都是表达看窗外的有效方式。例如：

I looked out the window and saw a beautiful sunset. (我朝窗外看，看到了一个美丽的日落。)

She looked outside the window and saw a bird on the tree. (她朝窗外看，看到了一只鸟在树上。)