How other clause types are derived from the declarative clause since it is structured in accordance with the complementation principles.
Considering the form and structure of sentences, we can identify types of sentences as declarative, imperative, interrogative and exclamatory. Most clauses (or simple sentences) fall into four basic categories, which are treated according to the clausal grammatical structure. These clause types are: declarative, interrogative, exclamatory and imperative; the following treatment is based on syntactic forms of given clauses. Declarative clauses have the structure the subject + the verb, which is the signal of an unmarked word ordering. The subject is thus an obligatory clause element. The declarative clause is treated as the default, basic type or unmarked type of clause due to the absence of other special features that make other types of clauses as marked. Declarative sentences always have a subject and a predicate. The subject can be simple with a noun phrase or it can be a compound subject. Compound subjects are made of more than one simple subject combined with a co...