because vs because of
RuleA conjunction joins two clauses (subject + verb); a preposition is followed by a noun phrase. Same meaning, different grammar.
Curiosity
"___ the rain, the event was delayed." because or because of? Both mean cause, yet only one fits.
Intuition
Look at what follows. A full clause (subject + verb) → conjunction (because, although, while). Just a noun phrase → preposition (because of, despite, during).
Visualization
See the parts: the connector is highlighted, and what follows is labeled "clause" or "noun phrase." The relation: "preposition + noun phrase (no verb)."
Check what follows: a clause or a noun phrase.
Because ofthe heavy rainthe event was delayed
Essence
Pairs: because (clause) / because of (noun); although (clause) / despite, in spite of (noun); while (clause) / during (noun). A TOEIC Part 5/6 favorite. Check whether a clause or a noun phrase follows the blank.
Examples
The flight was canceled because of the storm.
The flight was canceled because the storm was severe.
Despite the delay, the team met the deadline.
Mini-quiz
"___ the budget cuts, the project continued." Which fits? (a noun phrase follows)