Explain the concept of complex sentences in grammar.

In grammar, a complex sentence is a type of sentence that consists of an independent clause and at least one dependent clause. An independent clause is a complete sentence that can stand alone and express a complete thought, while a dependent clause is a sentence fragment that relies on the independent clause to form a complete thought.

The dependent clause in a complex sentence functions as an adverbial, adjectival, or nominal clause, providing additional information or modifying the independent clause. It adds complexity and depth to the sentence by introducing subordinate ideas or clauses.

There are three main types of dependent clauses in complex sentences:

1. Adverbial clauses: These clauses modify the independent clause by providing information about time, place, reason, condition, purpose, or manner. For example, "After I finish my homework, I will go to the movies." The dependent clause "After I finish my homework" modifies the independent clause "I will go to the movies" by indicating the time when the action will take place.

2. Adjectival clauses: These clauses modify a noun or pronoun in the independent clause, providing additional information or describing the noun. For example, "The book that I borrowed from the library is very interesting." The dependent clause "that I borrowed from the library" modifies the noun "book" by specifying which book is being referred to.

3. Nominal clauses: These clauses function as a noun within the independent clause, acting as the subject, object, or complement. For example, "What she said surprised me." The dependent clause "What she said" acts as the subject of the sentence, replacing a noun.

Complex sentences allow writers to express more nuanced ideas and relationships between different parts of a sentence. They enhance the clarity and coherence of writing by providing additional information, explaining cause and effect, or showing relationships between ideas. Understanding and using complex sentences effectively is crucial for constructing well-structured and sophisticated writing.