Here are the answers of the given questions above:
18. The sentence that contains an error in colon usage is option C. Brandon wanted to go fishing: but I wanted to go sailing. In this sentence, it should be a comma and not a colon.
19. An example of an indirect quotation would be option D. The lawyer said that your case will not take long. Indirect quotations no longer need quotation marks.
Leartes and Fortinbras share the same fate as Hamlet, the three of them lost their fathers in unfortunate circumstances. They feel the same kind of grieve of losing a loved one. But each reacts, differently. Their behaviour play a close related trait towards advice and duty, action versus inaction and sanity versus madness. Hamlet and Leartes want to get revenge, while the first is looking forward is getting the throne back and considers the consequences of his actions. Leartes, on the other hand, is blinded by his feelings (madness) and takes belligerent actions without thinking on the consequences.
Hamlet and Fortinbras, want to take revenge both. Whereas Hamlet only seeks to get the throne back and keeps on devating on how and when to take action, Fortinbras wants to clean his family's name and fights in an orderly fashion, with the use of an army.