Prepositions and conjunctions

Prepositions show relationships#

A preposition commonly appears before a noun phrase and shows its relationship to another part of the sentence: in the folder, after lunch, through the window, with care.

Choose by meaning. We say at a point in time, on a day or date, and in a broader period: at 9:00, on Monday, in August. These are patterns, not interchangeable labels.

Coordinating conjunctions#

Words such as and, but, or, so, and yet can join balanced words, phrases, or independent clauses.

• “Read the lesson and try the quiz.”
• “The method is short, but it is reliable.”

When joining two independent clauses, a comma normally appears before the coordinating conjunction.

Subordinating conjunctions#

Words such as because, although, if, when, and while introduce a dependent clause.

“Because the example was clear” cannot normally stand alone. Attach it to a complete clause: “Because the example was clear, the learner applied the rule.”

Logical precision#

Connectors carry meaning. Because gives a reason, although signals contrast, if sets a condition, and therefore states a result. Using a connector with the wrong relationship can make a grammatically complete sentence logically confusing.

Common mistakes#

Avoid doubling connectors in standard formal English: “Although it was late, but we continued” uses two contrast markers. Keep one. Also watch sentence fragments that begin with a subordinating conjunction but never reach an independent clause.

Final check#

Read the connected ideas separately. Decide whether they are balanced or one depends on the other, then choose the connector that states the relationship accurately.