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TOEIC Part 5 Grammar Trap

TOEIC Trap: Because vs Because Of

Because and because of both introduce reasons. The deciding clue is the grammatical structure that follows.

The structure rule

This page teaches the main sentence-level choice. For a deeper comparison with due to, continue to Because / Because Of / Due To. For reason versus contrast logic, continue to Because vs Although.

We cancelled the event because the weather was dangerous.

We cancelled the event because of the dangerous weather.

Standard-English rule: because is followed by a clause. Because of is followed by a noun or noun phrase.

The source’s “reason sentence / reason thing” wording is useful as a memory shortcut. The grammatical labels are clause and noun phrase.

Look immediately after the blank

You usually do not need to translate the whole sentence first. Identify what begins after the blank.

because + clausebecause the meeting was cancelled
because of + noun phrasebecause of the cancellation
due to + noun phrasedue to bad weather
Key distinctionclause = subject + verb; noun phrase = a person, thing, event or situation expressed as a noun group

Because: followed by a clause

Use because when the reason is expressed as a clause with its own subject and verb.

The shipment was delayed because the truck broke down.

We changed the schedule because several staff members were absent.

The client was satisfied because the team responded quickly.

Fast structural check: after the blank, can you identify who or what is doing or being something? If so, because may fit.

Because of: followed by a noun phrase

Use because of when the reason is expressed as a noun or noun phrase.

The shipment was delayed because of heavy traffic.

We changed the schedule because of staff shortages.

The client was satisfied because of the team’s quick response.

Articles, possessives and noun groups after the blank often point towards because of: the delay, its location, heavy traffic.

A common structure trap

A Part 5-style item can make both choices look close in meaning. The words after the blank decide which structure is grammatical.

Correct: The office closed early because the storm became severe.

Correct: The office closed early because of the severe storm.

Incorrect: The office closed early because of the storm became severe.

Better decision: Do not stop at “this gives a reason.” Ask whether the reason after the blank is a clause or a noun phrase.

Quick TOEIC check

Q1-Q4 are preserved from the supplied source. Q5-Q8 extend the same structure check.

1. The flight was delayed ___ heavy snow.
2. The flight was delayed ___ heavy snow blocked the runway.
3. The meeting was postponed ___ the manager was unavailable.
4. The meeting was postponed ___ the manager’s absence.
5. Production slowed ___ several machines were being repaired.
6. Production slowed ___ repairs to several machines.
7. The conference ended early ___ the venue lost power.
8. The conference ended early ___ a power failure at the venue.

Do not diagnose from one mistake

If this distinction causes repeated errors across several questions or timed sets, look at the decision pattern behind them.

Speed TrapYou choose from meaning before checking the structure after the blank.
TranslatorYou translate both forms as one Japanese reason expression and miss the clause/noun-phrase difference.
MemoriserYou remember a phrase but not the grammar pattern that controls it.
Over ThinkerYou know the rule but keep rereading instead of identifying the structure and deciding.

A single missed item is not enough to establish a Learning Block. Look for repeated evidence.

Final takeaway

because + clause

because of + noun / noun phrase

On a Part 5-style question, check the words after the blank first. Name the structure, then choose the connector.

Practise the structure, then review the pattern

Use focused grammar practice for the structure itself. If the same decision problem keeps returning across several questions, use the Learning Block Diagnostic to review how you are making the choice.

Open Grammar DrillsTake the Learning Block DiagnosticCheck your TOEIC study plan

Continue reading

Back to topTOEIC Part 5 GuideBecause / Because Of / Due ToBecause vs AlthoughDespite vs AlthoughLearning Block DiagnosticGrammar Drills
🔍 SEO FAQ — Because vs Because of What is the difference between “because” and “because of”? “Because” is followed by a full sentence. “Because of” is followed by a noun or noun phrase. How can I know if I should use “because” or “because of”? Check what comes after: if it’s a sentence with a subject and verb, use “because.” If it’s just a noun, use “because of.” Can I say “because of he was late”? No. That’s incorrect. Use “because he was late” or “because of his lateness.” Is “because of” always followed by a noun? Yes. “Because of” must be followed by a noun or noun phrase, not a full sentence. Can I start a sentence with “because of”? Yes. For example: “Because of the storm, the meeting was canceled.” What’s wrong with “because of it was raining”? It’s incorrect because “because of” cannot be followed by a sentence. Use “because it was raining” or “because of the rain.” How do I avoid the ‘because vs because of’ mistake in TOEIC? Look at what comes after the blank. If there’s a verb, use “because.” If not, use “because of.” Which is more formal: because or because of? Both are neutral in tone. Neither is considered more formal in TOEIC. Is it okay to use “due to” instead of “because of”? Sometimes yes, but TOEIC tests them separately. Use “because of” unless you’re sure. Can “because” come at the beginning of a sentence? Yes. For example: “Because he was late, we started without him.” What’s the TOEIC trick with “because” and “because of”? TOEIC gives you both as choices. The trick is to test your understanding of structure, not just meaning. Why does “because of” need a noun? It’s a fixed phrase that connects to a cause, not a full action. Is “because of rain” correct? Yes. “Rain” is a noun, so this is a correct use of “because of.” Is “because it rained” correct? Yes. That’s a proper use of “because” followed by a full sentence. Can I use “because” without a subject? No. “Because” must be followed by a subject and verb. Can I say “The match was postponed because the rain”? No. That’s incorrect. It should be “because of the rain” or “because it rained.” Why did TOEIC mark “because of he was late” as wrong? Because you used “because of” with a sentence. It should be “because he was late” or “because of his lateness.” What part of TOEIC tests “because vs because of”? Mainly Part 5 (grammar fill-ins) and sometimes in Part 3/4 listening. Is there a shortcut to check between “because” and “because of”? Yes. If what follows could be a full sentence, use “because.” If it’s just a noun, use “because of.” Can I just memorize examples to get this right? That helps, but spotting whether what follows is a sentence or not is faster and more reliable.