While the other sections in this module describe how sentences are constructed, this section describes why they have been written: to state facts, conjectures or arguments, give commands or ask questions.
It is quite common for entire texts or reports to be written using only declarative sentences. This type of sentence simply states a fact or argument without requiring an answer or action from the reader.
Declarative sentences are punctuated with a period:
Note that the last example is an indirect question, which is not the same as an interrogative sentence. Only a direct question makes a sentence interrogative.
An interrogative sentence asks a direct question and always ends in a question mark:
Note that an indirect question does not make a sentence interrogative:
A direct question requires an answer from the reader, while an indirect question does not.
As a general rule, since texts are written to present information or to make an argument, they do not contain many direct questions. There is, however, a special type of direct question called the rhetorical question—that is, a question that the reader is not expected to answer:
If not overused, rhetorical questions can be a very effective way to introduce new topics; if this device is used too often, however, the writer may sound patronizing.
An exclamatory sentence, or exclamation, is simply a more forceful version of a declarative sentence marked at the end with an exclamation mark:
Exclamatory sentences are common in speech and (sometimes) in fiction, but over the last 200 years they have almost entirely disappeared from formal writing, except for direct quotations. Note that an exclamation mark can also appear at the end of an imperative sentence.
An imperative sentence gives a direct command. This type of sentence can end either with a period or with an exclamation mark depending on how forceful the command is:
You should not generally use an exclamation mark with the word please:
You should avoid imperative sentences in formal writing. If you use an imperative sentence, it should contain only a mild command and end with a period: