Prepositions and conjunctions are the connecting elements in sentences. Finding the link between words is the secret to identifying prepositions. There are two guidelines about using prepositions: Avoid unnecessary prepositions, and avoid ending sentences with prepositions.
Conjunctions are parts of speech that connect words, phrases, or clauses. There are three types of conjunctions: coordinating, correlative, and subordinating. They are the keys to logically constructed sentences.
Interjections are used to express strong or sudden emotion and are usually grammatically separate from other sentences. Interjections are most effective when used sparingly.