It is Sam Border if you didn't know. To know what a main character is it is the character who is talked about throughout the whole book and/or is on the cover on the book. It is a strategy to know the main character(s) of the book. I hope this helps.
Answer:
memories of is how you fel ther you have to write
He can use a certain type of instrument or certain type of academic subject to narrow down the focus of his research.
