IQ is supposedly static, from what i understand. Other then some variation as the test gets harder and changes a bit for age brackets, intelligence once you reach a certain age (20 maybe? something like that) is the same throughout. But your work ethic is really what determines what you can do as far as school goes. For example, my older brother is the smartest of all of my siblings and me, but he is so apathetic that it is hard to convince him to get up in the morning and brush his teeth, let alone get a job or go to school. Me and my other brother, though we may not have as high an IQ go to school everyday, and work hard to get what we want and therefore are a lot farther in life then the other brother will ever get because he just doesnt care enough to get there.
So I wouldnt worry that you wont be able to learn anything new. The mere fact that it scares you seems to me to be proof that you wont have an issue at all.
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"We're like two children on the playground of the unconfessed souls
abandoned by our mothers and our lovers and our foes..."