Oh, what a lovely question! Here's a little sentence for you: "She spent hours in front of the mirror, admiring her reflection, but deep down she knew her obsession with her appearance was quite vain." Remember, it's important to appreciate the beauty within ourselves and others, just like we appreciate the beauty of nature.
In vain is means not effective, useless For an example: His discussion about changing the uniform is in vain
I pray the soldiers did not die in-vain.
The adverb of the word "vain" is vainly.An example sentence is: "she vainly checks her hair again".
Indentured servants were forced into slave-like labor as a result of vain pursuit of a better life.
The vain young lady was late to the funeral due to not being able to decide what to wear.
She spent hours in front of the mirror, preening and admiring her reflection, showing how vain she was.
The word "vain" means overly concerned with one's own appearance, or conceited. Examples : "My sister is so vain that she talks to herself in the mirror." Examples : " The vain man constantly worried about losing his hair." The word can also mean futile or fruitless, as in a vain attempt to escape from prison.
Vain means conceited, or it may mean to no avail. Here are some sentences.She tried in vain to stand on her head.He was as vain as a peacock."You're so vain!" (a song by Carly Simon)
I am not writing a sentence using that word.
a sentence using the word endotracheal
This is a sentence using the word aviator.
The spelling you are looking for is "vein" describing style or a distinctive element or maybe a line of thought or action. The word "vein" that you are looking for in your sentence is a noun. The word you used "vain" is an adjective meaning conceited, idle, empty, hollow, etc. and cannot be used as a noun or, from what I can see, in your sentence.