When I was in the plane I crossed a Land Plain
The word 'plain' usually means self-evident, without adornment, or a land form. To use these in a sentence: SELF EVIDENT: "It was plain to the police officer that the criminal has been wounded" WITHOUT ADORNMENT: "She had a very plain and ordinary face with no distinguishing characteristics." LAND FORM: "That is a very flat plain."
It's plain to see that you have never used the word plain in a sentence!
you are just plain ugly.
plain girls don't get dates unless they.... (incomplete sentence)
A plain
She wore a plain shirt. That is a very plain design. Plain as can be, he walked over here.
costul plain
She is not overly beautiful, nor ugly- just plain Jane.
I live in a flood plain, along with many others.
Coastal Plain
The land is flat with a lot of mountains
A large piece of flat land is called a plain. A mountain desert refers to a desert area with significant mountainous terrain.