Is that University of Pennsylvania or Penn State University? In all four cases these schools are HIGHLY competitive. You must have extremely good grades, extracurricular activities, references and excellent test scores, including SAT/ACT/TOEFL. I suspect their admissions will close early, but there's always a chance. You could call the admissions offices of each school. The one thing that the US has is lots of colleges and universities. Many of the state schools are very happy to take international students, especially when they pay their own way! I would suggest that you sit down with a guidance counselor and look at all your options, but quickly. You will be running out of time if you haven't taken your standarized tests. There will be a college or university for you, but it will take time and effort to find it. Meanwhile, have you thought about the American universities here? Even if you want to go to school in the States you could start here at one and transfer next year. They are set up so that all credits will transfer easily.
Mandi