Several years ago I returned to Washington,D.C.,and visited one of my old neighborhoods.I had been on Nash Street for more than twenty years and as I walked along the street,my mind was flooded by waves of nostalgia(怀旧).I saw the old apartment building where I had lived and the playground where I had played.As I viewed these once familiar surroundings,images of myself as a child came to mind.However,what I sawand what I remembered were not the same.I sadly realized that the best memories are those left undisturbed.As I remember my old apartment building,it was bright and alive.When I was a child,the apartment building was more than just a place to live in.It was a medieval castle,a pirate's den,a space station,or whatever my mind could imagine.I would always be excited because it was so cool and dark,and there were so many things there to hide among.