question: and insist upon that a computer is nothing but a new tool.
Capitalize this past sentence correctly.
A: And insist upon that a computer is nothing but a new tool.

question: the back is laminated wood with fixed inner padding.
Capitalize this past sentence correctly.
A: The back is laminated wood with fixed inner padding.

question: accidental file deletion: this is the most common mistake committed by many mac users.
Capitalize this past sentence correctly.
A: Accidental File Deletion: This is the most common mistake committed by many Mac users.