1. A declarative sentence. A declarative sentence states a fact and ends with a period / full stop.
(Remember, a statement which contains an indirect question (like this example) is not a question.)
2. An imperative sentence. An imperative sentence is a command or a polite request. It ends with an exclamation mark or a period / full stop.
3. An interrogative sentence. An interrogative sentence asks a question and ends with a question mark.
4. An exclamatory sentence. An exclamatory sentence expresses excitement or emotion. It ends with an exclamation mark.
The Four Sentence Structures
A sentence can consist of a single clause or several clauses. When a sentence is a single clause, it is called a simple sentence (and the clause is called an independent clause). A sentence must contain at least one independent clause. Below are the four types of sentence structure:
Complex Sentence A complex sentence has an independent clause and at least one dependent.
Compound Sentence - A compound sentence has at least two independent clauses.
Simple Sentence - A simple sentence has just one independent clause.
Compound-Complex Sentence - A compound-complex sentence has at least two independent clauses and at least one dependent clause.
What Is a Phrase?
A phrase is a group of words that stand together as a single unit, typically as part of a clause or a sentence.
A phrase does not contain a subject and verb and, consequently, cannot convey a complete thought. A phrase contrasts with a clause. A clause does contain a subject and verb, and it can convey a complete idea.