According to their meaning and word order, sentences are divided into four classes – assertive, imperative, interrogative and exclamatory. But according to their clause structure, sentences can be divided into four different kinds - simple, compound, complex and compound-complex.
The Simple sentence
Look at the following sentences.
- The sky is blue.
- The cow gives milk.
- The sports meet will be held tomorrow.
These sentences have only one subject and one predicate each. A sentence which has only one subject and one predicate is called a simple sentence.
The Compound sentence
Read the following sentences
- He went to the airport and boarded the evening flight.
- You can have tea or coffee.
- He went to the store, bought some books and came back.
The sentence 1 has two parts: He went to the airport and he boarded the evening flight joined by the coordinating conjunction and. Each part has its own subject and predicate and therefore each is a clause. Moreover, they are clauses of equal rank or importance, independent of each other. Such clauses are called co-ordinate clauses.
Sentence 2 is a combination of two independent clauses of equal rank: you can have tea and you can have coffee, joined together by the coordinating conjunction or. Sentence 3 has three independent clauses of equal rank – He went to the store, he bought some books, he came back - and these are joined together by the coordinating conjunction and.
A sentence which has two or more coordinate clauses is called a compound sentence.