We learned that a compound sentence is two complete thoughts joined together.
A complex sentence is also two thoughts joined together, but the two thoughts are not equal. One thought is an independent clause. The other thought is a subordinate clause (or dependent clause).
An independent clause is strong enough to stand alone.
A subordinate clause can’t stand alone. It must be connected to an independent clause.
A subordinate clause always begins with a subordinating conjunction. I call these words subordinate clause words.
Some Subordinating Conjunctions
- after
- although
- because
- before
- if
- since
- unless
- until
- when
- where
- while
- who
When you start a sentence with a subordinate clause word, you are starting a complex sentence. The sentence will not be complete until you add an independent clause.
Here is a clause beginning with the subordinating conjunction When:
When it stops raining
This clause is not a sentence because it cannot stand alone. It does not make sense. We read it and wonder what comes next.
If you start a sentence with a subordinate clause, you must add an independent clause. Now this sentence is complete. It makes sense.
When it stops raining, the baseball game will start.
Join an independent clause and a subordinate clause to make a complex sentence. Plain and simple.