a student went to see a doctor, after the examination, the doctor said,"don't worry(no problem), you just need to get a shot." the doctor wiped the student's arm with cotton, suddenly, the doctor put the cotton close to his eyes and looked at it, then wiped the student's arm again, this happened three or four times. the student thought he was seriously ill, so he asked the doctor anxiously, "doctor, is my illness really serious(am i really sick?)" the doctor answered seriously, "student, you should go take a shower...