The Environmental Protection Agency was once forced to buy an entire town because dioxins had rendered it uninhabitable. The story was not only long but also dull. I did not know whether to laugh or cry after I realized my mistake. Exhausted men and women worked the pumps until their arms ached. Although I live in a big city, my neighborhood has enough trees and raccoons to make me feel as if I live in the suburbs.
Interjections often stand alone, as fragments.
Even when they are included in a sentence, they are not related grammatically to the rest of the sentence. The fans screamed, jumping to their feet. The problem suggested, alas, no easy solution.