A complex sentence is made up of two clauses: an independent clause and a subordinate clause. Today we will practice writing complex sentences with the subordinate clause words while, when, whenever, unless and until.
Here is a complex sentence beginning with the subordinate clause word while:
While you are waiting, I will get the mail.
We put a comma after the subordinate clause before adding the independent clause.
If we put the independent clause first, we don’t need a comma.
I will get the mail while you are waiting.
This sentence says the same thing as the previous sentence. We just rearranged the two clauses.
Here are more examples. Look carefully to see how a sentence loses the comma when we move the subordinate clause.
When the rain stops, we can play tennis.
We can play tennis when the rain stops.
Whenever you are ready, we can leave for the theater.
We can leave for the theater whenever you are ready.
Unless I find my mittens, I can’t play in the snow.
I can’t play in the snow unless I find my mittens.
Until bell rings, we have to stay in our seats.
We have to stay in our seats until the bell rings.
Subordinate clause words while, when, whenever, unless, and until always signal the beginning of a subordinate clause. Any sentence with a subordinate clause is a complex sentence. If you begin a complex sentence with the subordinate clause, you need a comma in the sentence. Don’t use a comma when the subordinate clause word is in the middle of the sentence.