A parenthetical element is any part of a sentence that adds extra information to a sentence.
The information is not essential to either the meaning or grammatical accuracy of the sentence, but it is probably useful or interesting.
The parenthetical element must be ‘set apart’ from the rest of the sentence with a comma, e.g.
Tomorrow, I will get my revenge.
The crocodile, who had developed a taste for human flesh, was hungry again.
The parenthetical element can be anything from a single word to several words, e.g.
My brother, fortunately, was eaten first.
My brother, who probably tastes as terrible as a dirty old recycling bin, was eaten first.
Depending on what part of the sentence it’s adding information to, the parenthetical element can come at the start, middle or end of the sentence. In some instances, it can work in all three places, e.g.
Looking hungry, the crocodile eyeballed me.
The crocodile, looking hungry, eyeballed me.
The crocodile eyeballed me, looking hungry.
One of the most common uses of parenthetical elements is as introductory elements that come at the start of a sentence. There are three common types of these:
Adverbial phrases (discussed in more detail in the section below), e.g. As quickly as possible, we should run from the house to the car.
Prepositional phrases (discussed in more detail in the section below), e.g. After dinner, the crocodile was hungry again.
Dependent clauses at the start of sentences e.g.
Rather than go for me, I secretly wished it would go for my brother.
While we sprinted for safety, I tried to create a diversion.
Remember: We need a comma after dependent clauses that begin sentences, e.g.
Wherever I go, the crocodile follows (dependent clause first; comma needed)
Unless I can escape, my death is inevitable (dependent clause first; comma needed)
Extra information:
Another relatively common use of parenthetical elements is before a ‘tag question’ (or a ‘question tag’). This is where we include a question word or phrase at the end of an utterance, usually to elicit an actual answer (usually in the form of agreement), e.g.
The crocodile is still there, right?
You didn’t know it was still there, did you?
His teeth are absolutely enormous, eh / ay?
Prepositional phrases are a type of phrase that can be used to start a sentence.
They give more information about the subject of the sentence, in particular, when or where something happens.
They start with a preposition (a word that shows the connection between two things. When used at the start of a sentence, the connection that the prepositional phrase shows is usually to do with:
Place (i.e. the physical relationship in space), e.g. In the recycling bin, Under the car, On the back of the crocodile.
Time, e.g. Before I ran, While I screamed, During my fight for survival.
Being a phrase, they are a group of words that have some meaning but don’t have a subject-verb combination: they’re missing either a subject and/or a verb (therefore, they’re not yet a clause).
As with all parenthetical elements, when they are used at the start of a sentence prepositional phrases must be ‘set apart’ from the rest of the sentence with a comma, e.g.
After dinner, the crocodile was hungry again.
Before anything else happens, I need to check that I have my crocodile repellent.
A verb phrase is a group of words that has a verb and other verbs connected to that verb, but that is missing a subject (so doesn’t form an independent clause).
Usually, verb phrases have verbs in ‘participle’ form. The ‘participle’ form of a verb is one of the main verb forms (the others are the ‘infinite’, simple past, and simple present).
The verbs can come in two types of participles:
Past participle, e.g. climbed
Present participle, e.g. climbing
The past participle (-ed):
The past participle is the form of the verb that usually ends with -ed, e.g. chewed, chased, worried.
The past participle communicates the idea that the action is finished or has been completed.
Note: Depending on the verb, the past participle verb form may end in any of these ways (depending on spelling):
-ed or -d, e.g. , jumped (from jump), spared (from spare)
-t, e.g. dealt (from deal)
-en or -n, e.g. bitten (from bite), taken (from take), worn (from wear)
When a sentence starts with a past participle, the phrase with the past participle needs to be ‘set apart’ from the rest of the sentence with a comma, e.g.
Chewed right through, the recycling bin couldn’t protect me any more.
Dealt a rough hand by Fate, I felt sorry for myself.
Spared by Fate for one more day, I vowed to get my revenge soon.
Worn to tatters, my shoes wouldn’t help me anymore.
The present participle (-ing):
The present participle is the form of the verb that ends with -ing, e.g. leaping, running, surviving.
The present participle communicates the idea that the action is ongoing.
When a sentence starts with a present participle, the phrase with the present participle needs to be ‘set apart’ from the rest of the sentence with a comma, e.g.
Leaping from the roof of one car to the next, I avoided the crocodile.
Running as fast as I could, I got ahead of my brother who was also fleeing.
Surviving another day, I vowed to get my revenge soon.
The present participle verb usually needs other words to form a phrase, but sometimes the verb alone is enough, e.g. Screaming, I ran as fast as I could.
Adverbs and adverbial phrases can be used as one type of parenthetical element when they are used to start a sentence.
They give extra information about the ideas in the sentence.
Remember: Adverbs often end with -ly.
Just like with a conjunctive adverb, when they start a sentence, they must be ‘set apart’ from the rest of the sentence with a comma, e.g.
Quickly, I sprinted to the front door.
Furiously, the crocodile snapped at my heels.
Their function can be to show what the writer thinks about the information in the sentence (without directly saying it), e.g.
Surprisingly, I made it inside the house. (This shows that the writer is surprised that they made it.)
Fortunately for me, I was a faster runner than my brother. (This shows that the writer realised that they have been fortunate.)
Regretfully for my mother, my brother was eaten. (This shows that the writer knows that their mother feels regret for what happened.)