A complex sentence is a sentence that contains one independent clause and at least one dependent clause. The independent clause can stand alone as a complete sentence, but the dependent clause cannot. The dependent clause adds information or explanation to the independent clause.

Here are some examples of complex sentences:

* **Independent clause + dependent clause:**
* The cat that was sitting on the mat ran away.
* I will go to the store after I finish my homework.

* **Dependent clause + independent clause:**
* Because it was raining, we stayed inside.
* When the bell rings, we will all go home.

* **Complex sentence with two dependent clauses:**
* Although I was tired, I still went to the party.
* I will not eat the cake because it has too much sugar.

As you can see, complex sentences can be used to add a lot of information to a sentence. They can also be used to make your writing more interesting and engaging.

Here are some tips for writing complex sentences:

* Use subordinating conjunctions to connect the independent and dependent clauses. Some common subordinating conjunctions are because, since, when, before, after, although, if, unless, and while.
* Make sure that the dependent clause comes before the independent clause.
* Use the correct punctuation to separate the independent and dependent clauses.

With a little practice, you will be able to write complex sentences that are clear, concise, and informative.