the words help bring the piece of writing to life. they may help in creating imagery, and they may even help the reader feel like they are involved in the story. the choice of words can also help set the mood for the story like mysterious, happy, sad, etc.
C. "An Occurrence at Owl Creek Bridge"
What do you mean? can you explain some more
1. The whole class laughed loudly at the story.
complete subject: the whole class
complete predicate: laughed loudly at the story
2. The whole class laughed loudly at the story.
simple subject: class
simple predicate: laughed
3. Twelve hours passed without a word from any of the group.
simple subject: hours
simple predicate: passed
4. The workmen repaired the dam.
complete subject: the workmen
complete predicate: repaired the dam