Explain the concept of compound-complex sentences.

Compound-complex sentences are a type of sentence structure that combines elements of both compound and complex sentences. In a compound-complex sentence, there are two or more independent clauses, which are complete sentences on their own, and at least one dependent clause, which cannot stand alone as a complete sentence.

The independent clauses in a compound-complex sentence are connected by coordinating conjunctions such as "and," "but," or "or." These conjunctions help to show the relationship between the independent clauses. For example, "I went to the store, and my friend bought some groceries."

Additionally, the dependent clause in a compound-complex sentence is introduced by subordinating conjunctions such as "although," "because," or "while." This dependent clause adds more information or provides a condition to the independent clauses. For example, "Although it was raining, we decided to go for a walk."

Compound-complex sentences allow for the expression of complex ideas and relationships between different parts of a sentence. They are commonly used in both written and spoken English to convey more nuanced and detailed information.