Conjunctions and Prepositions in Complex Sentences

Coordinating conjunctions, such as 'and,' 'but,' 'or,' 'so,' and 'yet,' connect two ideas of equal weight. In "The trail was steep, but the view was worth it," 'but' connects two complete ideas and signals contrast between them.

Subordinating conjunctions, such as 'because,' 'although,' 'since,' and 'while,' connect a main idea to a supporting idea that cannot stand alone. In "Although the trail was steep, we kept climbing," 'although' attaches a dependent idea to the main sentence and shows a relationship of contrast or condition.

Correlative conjunctions work in matched pairs, such as 'either / or,' 'neither / nor,' and 'not only / but also.' In "Not only did we reach the summit, but we also watched the sunrise," the paired words connect two balanced ideas across the sentence.

A preposition shows a relationship between a noun or pronoun and another word in the sentence, usually a relationship of place, time, or direction. Simple prepositions use one word, like 'under,' 'during,' or 'across.' Compound prepositions use more than one word to do the same job, like 'in front of' or 'next to.'

A prepositional phrase is the preposition plus its object and any describing words in between, such as "across the rocky ridge." The object of the preposition is the noun that answers 'what' or 'whom' after the preposition, so 'ridge' is the object in that phrase. A prepositional phrase can describe a noun, which makes it work like an adjective, or it can describe an action, which makes it work like an adverb. In "the trail through the forest," the phrase describes the noun 'trail.' In "we hiked through the forest," the same kind of phrase describes the action 'hiked' instead.

Try this sentence: "Although the hikers were exhausted, they pushed across the ridge because they wanted to watch the sunrise from the summit." Work through it piece by piece.

'Although' is a subordinating conjunction. It joins the dependent idea "the hikers were exhausted" to the rest of the sentence and signals contrast. 'Across' is a preposition starting the phrase "across the ridge," which tells where the hikers pushed, so it works like an adverb describing the verb 'pushed.' 'Because' is another subordinating conjunction, this time joining a reason to an action. 'From' begins the phrase "from the summit," which describes where the sunrise would be seen.

Notice how one sentence can hold two subordinating conjunctions and two prepositional phrases at once. Explaining the function of each word, not just naming it, is the real skill: say what idea it connects, or what relationship it shows.

Coordinating Conjunction: A word that joins two ideas of equal importance, like 'and,' 'but,' or 'or.'

Subordinating Conjunction: A word that joins a dependent idea to a main idea, like 'because,' 'although,' or 'since.'

Correlative Conjunction: A pair of words that work together to join balanced ideas, like 'either / or' or 'not only / but also.'

Preposition: A word that shows a relationship of place, time, or direction between words, like 'under' or 'before.'

Compound Preposition: A preposition made of more than one word, like 'in front of' or 'next to.'

Prepositional Phrase: A preposition, its object, and any describing words, such as 'through the dark forest.'

Object of the Preposition: The noun or pronoun that follows a preposition and answers 'what' or 'whom.'

Underline every conjunction in a paragraph and label each one as coordinating, subordinating, or correlative. Then circle every preposition, bracket its full phrase, and decide whether that phrase describes a noun or an action. Rewrite a short sentence three times using a different kind of conjunction each time to see how the relationship between ideas changes.

Related lessons

• Understanding Conjunction Functions Explaining Preposition Uses Identifying