How to know if a (male 17/18) classmate crushes on you?

I'm a 18 year old female that sometimes wonders if the guys from my class crush on me since there are lot's of awkward moments. Some tease me a lot, some don't talk to me a lot but stare at me so much and some are bluntly mean. What are the signs a teenage guy likes you? I'd like to know.

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I'd like to add: they NEVER say something mean about my appearance. If they tease me it is ab things that I did or do.
How to know if a (male 17/18) classmate crushes on you?
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