What would be your answer if someone asked you what a language is according to you? A medium for communication? A composition of words, phrases and clauses to form sentences? Yes, a language consists of words, phrases and clauses that are combined to make complete and meaningful sentences, thereby making communication possible.
In the English language, each word in a sentence can be categorised into one of the parts of speech. A sentence can consist of a noun, a verb and another noun; a noun, a verb and a noun phrase; a noun, a verb and an adverb; a noun, a verb and a prepositional phrase and so on. Nouns and verbs are considered to be the essential parts of a sentence. A sentence does not exist without a noun and a verb.
Among the parts of speech, there are words that are employed in a sentence just to provide more information about the nouns and some others to modify the verb. The part of speech called adjectives are used to describe the noun and give further information about the noun to the reader or listener. Adjectives include words that signify qualities and characteristics like good, bad, smart, tall, thin, black, egoistic, honest, clever, happy, excited, depressed and so on. Any descriptive piece of writing will have plenty of adjectives. Adjectives seem to give the reader or listener a very clear picture of what kind of a person, what sort of thing/idea and what type of place the speaker/writer is mentioning.
Adverbs, on the other hand, are employed in a sentence to modify the verb, the adjective or another adverb used in the sentence. Unlike other parts of speech, an adverb can be used multiple times and in the beginning, middle or end of a sentence. Words that denote the time, place, manner, frequency and degree of an action or a quality can be classified as adverbs. Some examples of adverbs would be quickly, happily, wholeheartedly, lately, rarely, never, yesterday, the day after tomorrow, annually, too, very, ghastly, etc.
Now that you know what kind of words to use to qualify a noun, verb, adverb or adjective, you should know what sort of words can be used to link them together. While a conjunction is meant to combine words, phrases and clauses to form sentences, a preposition is used to link one part of the sentence to another. For instance, in the sentence, I left the book on the table, the first part of the sentence, ‘I left the book’ is connected to the latter, ‘the table’, by means of the preposition ‘on’. In other words, a preposition mentions where some object has been placed or where exactly something, someone or someplace is.
If you think that a sentence does not necessarily require a preposition, an adjective, a conjunction or an adverb, you are right. However, with just verbs and nouns, you will not be able to give your reader or listener any extra information regarding the noun/pronoun that acts as the subject/object in the sentence or the way an action is taking place. If you are seeking to draft a descriptive or narrative piece of writing, you will have to include prepositions, adjectives and adverbs to make the writing look and sound sensible and informative.