What are affirmative, complex, compound, and simple sentences? How do you change the voice of a sentence, or change a sentence from positive to negative?

Expert Answers
mwestwood eNotes educator| Certified Educator
  • An affirmative sentence--also called a declarative sentence--is a sentence that forms a statement; it states an idea and ends with a period. e.g. "Necessity is the mother of invention."
  • A complex sentence consists of one independent clause (this can stand alone as a simple sentence and is sometimes called a main clause) and one dependent clause (also called a subordinate clause--it cannot stand on its own as a sentence). The dependent or subordinate clause often begins with a subordinating conjunction such as after, although, because, before, even though, until, when, where, while, etc. e.g. "No one answered [=independent clause] when she called [=dependent clause]."
  • A compound sentence is composed of two main clauses joined by a coordinating conjunction. It is essentially two simple sentences put together into one sentence. e.g. "We can go to the beach today,|| or we can wait for better weather. [Before the || is the one main clause. After the conjunction or is the second main clause.]"
  • A simple sentence is like a main clause. It consists of a single independent, or main clause, with a period at the end. e.g. "It has rained."          


Voice is the form of a verb that indicates whether or not the subject of the sentence is doing the action that the verb indicates.

  • In active voice, the subject is the doer of the action. e.g. "Laura[=subject] found[=verb] a gold bracelet yesterday."
  • In passive voice, the subject receives the action (the subject is verbed). e.g. "A gold bracelet was found by Laura." (Here the subject is the bracelet, and the bracelet is acted upon by Laura.)

NB: Notice, too that the predicates (verbs) differ in active and passive voice. In passive voice the past participle is always used, and the helping verb be precedes this main verb. So, in passive voice there are always 2 verbs in a verb phrase: the verb to be in whatever tense is needed (is, are, was, were, has been, have been, will have been), followed by the main verb, which is in the past participle form ("the bracelet was found").    

  • Changing the voice from active to passive: Move the subject to after the verb or verb phrase, and change the verb to the passive form with a tense of to be +the past participle. (Active Voice sentence: "Grandfather blew up the balloon for Casey." Passive Voice sentence: "The balloon for Casey was blown up by Grandfather.")
  • Changing the voice from passive to active: Move the doer of the action to the position of the subject, and have him/her performing this action. (Passive Voice sentence: "Janice's clothes were tossed randomly into the closet." Active Voice sentence: "Janice tossed her clothes randomly into the closet.")
  • Changing from a positive to a negative sentence: In order to negate a sentence, the most common way is to insert the word not before the main verb. Sometimes do or does accompany the main verb and the not, and at other times negatives such as neither....nor or never or not ever are used as negatives instead of not. e.g. "Sally has not eaten supper tonight. I do not like brussel sprouts." "No, neither I nor my friend are coming to the party.  Sue never comes."
  • Using a question tag  Question tags such as aren't you? isn't he? aren't we? aren't I? etc. or don't you? haven't you, doesn't he? won't they? won't we? etc. are used after a declarative sentence in order to change it to an interrogative one (to which the listener will hopefully agree to the suggestion made in the question). e.g. "That little dog is so cute, isn't he?" "We are going to stop to eat soon, aren't we?" Sometimes the listener responds negatively, however: "You like your new car, don't you?" "No, I'm afraid I don't."
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The Practice of Writing

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