adding dashes where needed
There was a loud boom -- what a fright from the back of the theater.
We all turned around -- I even jumped up to see what it was.
It was part of the play -- imagine that meant to add suspense.
I'd love to see the play again -- maybe next week -- and bring Andrea.
The fourth sentence is correct.
Study this carefully and re-think the other sentences.
http://grammar.ccc.commnet.edu/grammar/marks/dash.htm
To add dashes where needed in the given sentences, you can follow a few punctuation rules. Dashes are used to indicate a sudden break or interruption in a sentence or to add emphasis. Here are the updated sentences with dashes correctly added:
1. There was a loud boom—what a fright—from the back of the theater.
2. We all turned around—I even jumped up—to see what it was.
3. It was part of the play—imagine—that meant to add suspense.
4. I'd love to see the play again—maybe next week—and bring Andrea.