Complex Sentences
Combining an independent clause and a dependent clause in a single sentence
Independent Clause + Dependent Clause
When you attach a dependent clause at the end of a main clause, you will generally not use a comma.
Tanya did poorly on her history exam because her best friend Giselle insisted on gossiping during their study session.
Jonathon spent his class time reading comic books since his average was a 45 one week before finals.
Dian decided to plant tomatoes in the back of the yard where the sun blazed the longest during the day.
Dependent Clause + , + Independent Clause
When you attach a dependent clause in front of a main clause, use a comma.
Even though the broccoli was covered in cheddar cheese, Emily refused to eat it.
Unless Christine finishes her calculus homework, she will have to suffer Mr. Nguyen’s wrath in class tomorrow.
While Bailey slept on the sofa in front of the television, Samson, the family dog, gnawed on the leg of the coffee table.
Relative Clause Punctuation
When the dependent clause starts with a relative pronoun, punctuation gets a little trickier.
When the information in the relative clause is essential, follow the above formulas (ID and D,I).
Nick gave a handful of potato chips to the dog who was sniffing around the picnic tables.
“dog” is a general noun
The relative clause clarifies which dog we mean and is essential
No comma necessary
The manwho was wearing a red shirtwished that he had instead chosen ketchup for his hotdog.
“man” is a general noun
The relative clause clarifies which man and is essential
No commas necessary
When the information in a relative clause is nonessential, you need a comma even if the relative clause is last (I,D).
Nick gave a handful of potato chips to Button, who was sniffing around the picnic tables.
“Button” is a specific noun
The relative clause is now nonessential
The relative clause must be set apart with commas.
Charles, who was wearing a red shirt, wished that he had instead chosen ketchup for his hotdog.
“Charles” is a specific noun
The relative clause is now nonessential
The relative clause must be set apart with commas