Introductory Participial Phrases
* Yes, they are usually set off by a comma. A participial phrase acts like an adjective modifying the noun or pronoun that follows. If it comes at the beginning of the sentence, it's usually set off by a comma to prevent confusion.
Example: *Walking through the park, Sarah noticed a squirrel hiding in the branches.*
* Exception: If the phrase is very short and essential to the meaning of the sentence, you can omit the comma.
Example: *Smiling broadly, the child reached for the cookie.* (The smiling is essential to understanding which child is reaching.)
Adverb Clauses
* Yes, they are usually set off by a comma. An adverb clause modifies the main clause and often expresses time, place, cause, or condition. When it comes at the beginning of the sentence, a comma helps to separate it from the main clause.
Example: *Because it was raining, we decided to stay inside.*
* Exception: Short adverb clauses that are essential to the meaning of the sentence can be omitted.
Example: *When you go to the store, buy some milk.* (The "when" clause is necessary to understand the action.)
Key Points:
* Purpose: Commas are used to separate introductory elements from the main clause to improve clarity and readability.
* Essential vs. Non-Essential: Whether or not a comma is needed depends on whether the introductory phrase or clause is essential to the sentence's meaning.
Let me know if you'd like more examples or have other grammar questions!