We have already learnt that a Complex sentence consists of a Principal or Main Clause with one or more Subordinate clauses. The clause which contains the main Verb of the entire Complex Sentence is called the Principal or Main Clause.
There are three kinds of Subordinate clauses.
1. The Noun Clause
2. The Adjective Clause
3. The Adverb Clause
A Noun Clause is one which does the work of a Noun in relation to some word in some other clause.
An Adjective Clause is one which does the work of an Adjective in-relation to some word in some other clause.
An Adverb Clause is one which does the work of an Adverb in-relation to some word in some other clause.