Answer:
The author’s main purpose in this excerpt is to describe a form of code writing using an example.
In the text in question, the author describes how General Clinton inserted a secret message in a text apparently unrelated to the information that he wanted to convey. That is, through a real situation, he exemplifies how a secret message could be introduced that changed the course of history.
Answer:
after she ran her marathon her legs were sore and she was tired, she had to rest for awhile.
I would think a unit of speech is the word...word. Letters make up a word. One word is not a sentence.