Why my female classmate is ignoring me?

She is a classmate, we dont talk much but we aren't unknown to each other, sometimes we make eye contact by anything (a joke, comment about the class, etc) I sit next to her but sometimes when she says some comments or information in class, I ask her back, she look at me, we make eye contact and turn her head quickly, ignoring completely my question. I wanna add that she is very friendly and I haven't had any trouble with her. I feel like she can't keep eye contact with me like my other classmates. Even though she look at me when we are sit far each other.
Why my female classmate is ignoring me?
Add Opinion