No, nouns are not used in every sentence.
A sentence requires only a subject and a verb. The subject may be a noun or a pronoun. Examples:
- "How are you?" "I am fine." (the pronouns 'you' and 'I' take the place of the nouns for the one spoken to and the speaker)
- "He made it himself." (the pronouns 'he' and 'himself' take the place of the noun for the person spoken about, the pronoun 'it' takes the place of the noun for the thing spoken about)
An imperative sentence that gives advice or instructions may consist of only a verb. The subject of an imperative sentence can be implied. Examples:
- "Look!" (the implied subject is 'you', a pronoun)
- "Drop it." (the implied subject is 'you, the direct object is 'it', both pronouns)
