Left
A deserted school: A <em><u>solitary</u></em> child <em><u>neglected</u></em> by his friends. I can only give the answer to this. There is no way to show that it is so. But you could look at the previous paragraph where Scrooge sees two people cross paths and wish each other a Merry Christmas. Right about now, Scrooge does not feel either Merry or Christmassy. What he does feel is the sight before him of a deserted School and a solitary and neglected child, which of course is himself. Does that not suggest loneliness?
Middle
Memories of childhood. No person my age ever forgets the movie <em><u>Treasure Island </u></em>and the remarkable frightening performance of Robert Newton as Long John. I walked around for months giving a poor imitation of his accent. It's a must see movie.
The paragraph you want is the line beginning "This was not the map we found in Billy Bones chest ... " The line you want is "Sharp as must have been his annoyance ..." He could control it. Silver could wait. There was time. No need to get upset. The real map would show.
Three
They disappeared because the mist enclosed them. It was as though they were covered by an outer piece of clothing which made them invisible to the ordinary on looker. The answer is surrounded. You can't eliminate the other answers. They just don't apply. The second best answer is protected, but the ghosts don't need protection. They can take care of themselves. They just need to be surrounded by the mist when they are done.