what i supported to do?

After sitting for final exam,i feel that i didn't perform well in my important exam which decide the chance for me to choose the course i wanted at university.I really think that i am so stupid until i can't do well in my exam.But,this is what i put my effort to do it,in turn maybe i make my parents disappoint in this time.I always tell myself that my parents sacrifice a lot of thing for me include they pay a lot of money for me to study at matriculation and also my previous tuition class and also other expenses.When i think about these, i want to study hard so that what they sacrifice for me will not in vain.However,i put my effort to do so but i still can't get good result bacause i am not a clever student and not even know how to apply my knowledge as my mum also say i am stupid.I really should recognize my limited ability.Why i want to be a doctor?Actually,i always say to myself,"if i become a doctor,i can even cure my father if he get any disease in the future.This is because my dad is a smoker and he also like to drink alcoholic beverage.These make me so worry about his condition.I ask him to stop the quantity of drinking alcohol and he always say :''ya ya" ,his answer is just neglect me.However what can i do is just paying nothing back to my parent.My parent say if i really can't do well in academic,it is not a problem because they don't want me to feel stress.Although my dad always say if i achieve success in my future and my success is the result of my effort.They don't hope me to return them anything .However, i know i should do something and achieve success in my life to make them proud of me.Pick myself up and what you think,our body can achieve it.Even though i am not a clever student,but now i am given chance to study and i should appreciate it.