题目

Mr. Patrick was new to the school and to us. Even though he was a great teacher, he seemed rather like a character out of a horror movie. He didn’t look that bad, but somehow, he looked extremely scary to me. Some kids began to believe that he was a murderer or a ghost; some believed he was mad and a few believed that he might have suffered a lot in his life. I was one of those ‘few’. One day I gathered up my courage and headed towards the school garden. He was, as usual, sitting on a bench alone. I breathed heavily a few times and then walked towards him. “How are you?” I a|a|=6，则a=________；化简：-[+（-5）]=________．