Rewrite each sentence correctly and then identify which comma rule applies.
Upon entering the room the detective noticed several possible clues.
Comma Rule: ______________________________________________________
Corrected Sentence: _________________________________________________
Upon entering the room, the detective noticed several possible clues.
Comma Rule: Use a comma to separate an introductory element from the rest of the sentence.
Corrected Sentence: The detective noticed several possible clues upon entering the room.