THE DANGLING PARTICIPLE
Adjectives ending in -ing (and sometimes -ed) are called participles and must be used with care:
"After rotting in the basement for weeks, my mother threw out some oranges."
Eeeeeeewwwwww! Your mother was rotting in the basement? The problem with the above sentence is that the participial phrase that begins the sentence is not intended to modify what follows next in the sentence. However, readers mentally expect it to work that way, so your opening phrase should always modify what immediately follows. If it doesn’t, you’ve left the participle, and your readers dangling.
"After rotting in the basement for weeks, my mother threw out some oranges."
Eeeeeeewwwwww! Your mother was rotting in the basement? The problem with the above sentence is that the participial phrase that begins the sentence is not intended to modify what follows next in the sentence. However, readers mentally expect it to work that way, so your opening phrase should always modify what immediately follows. If it doesn’t, you’ve left the participle, and your readers dangling.