what's the differences of the college entrance exam between china and US?  

firstly i would like to tell something about myself ,I come from china ,and i was able to be admitted to the college last year ,most importantly the college is exactly the one i want to go to ,i think most of the americans know very little about the college entrance exam in china just like we know about america ,this is why i start this disussion,I have heard that there were 6 collgege entrance exam in US per year ,and everyone can decide on his own which exam is to take ,but the fact is that we have only one collge entrance exam in the whole year!what's worse ,the only criterion to judge whether a person is qualified for college is his performance in the exam ,it means that ,once you fail in the exam ,you will bhave to wait for one year before the begining of the next exam ,as i just know very little about the situatiou in US ,i will really appreciate it if you guys are willing to tell me the further information about this topic ,and at the same time you guys will know about it from me ,thanks .