For capital letters, we can just add the ending -s, for example:
I got As in the final exam.
for lower-case letters, an apostrophe is used to avoid confusion:
In the multiple-choice exam all the correct answers happened to be a's! (as in: option a)
It is true that any interpretation that can be defended with evidence from the text is a valid topic for a critical essay.
My name is liz
It is a challenge that the main character must face in order to progress through a usually conflicting story to restore order to their world or to grow as a person.
The animal who is the first to commit the rebellious act is Napoleon. He had Snowball chased from Animal Farm using nine vicious dogs. After Snowball's exile, Napoleon assumed leadership.