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TOEIC Grammar Trap · Part 5

TOEIC Word Families: Choose the Right Form Under Pressure

In TOEIC Part 5, answer choices can look almost the same: success, successful, successfully, succeed. The meaning is connected, but only one form fits the blank.

This page teaches the main word-family decision skill. For deeper TOEIC word-form traps such as effect / affect, efficient / efficiency, and approve / approval, continue to Word Families Part 2.

For broader clue-first Part 5 practice across grammar patterns, use the separate TOEIC Part 5 Grammar Drills hub.

The company’s recent success led to a major contract.

The company launched a successful campaign.

The campaign was completed successfully.

The company hopes to succeed in the Asian market.

MTC coaching rule: Do not choose by meaning first. Find the job of the blank, then choose the form that can do that job.

The MTC 7-second choice

Nearby words can give useful signals about the job of the blank. This is an MTC coaching heuristic, not an official TOEIC timing rule.

Thing or ideaLook after a, the, this, recent, company’s, applicant’s.
Describes a thingLook before a business thing such as report, launch, plan, or employee.
Describes an actionLook near action words such as completed, responded, changed, or worked.
Action after toIn many TOEIC patterns, to is followed by an action form.
After a prepositionAfter with, for, of, by, in, check whether the phrase needs a noun or noun phrase.
After beCheck whether the sentence needs a result description: was successful.

Pattern one: the blank is a business thing or idea

If the blank follows words such as the, a, recent, final, company’s, or applicant’s, check whether the sentence needs a noun or noun phrase.

The company’s recent success attracted new investors.

The applicant’s experience impressed the hiring manager.

Management will announce its final decision tomorrow.

Fast check: if the sentence needs “what thing?” or “what idea?”, do not choose the action or description form.

Pattern two: the blank describes a business thing

If the blank comes before a business noun, check whether the answer needs to describe that noun.

a successful launch

an applicable rule

a competitive price

a decisive manager

The useful question is not “What does the word mean?” It is “What kind of thing is this?”

Pattern three: the blank describes an action or result

If the blank modifies an action, change, or result, check whether the sentence needs the form that tells how something happened.

The installation was completed successfully.

The team responded quickly to the request.

The price increased significantly last quarter.

This contrast can make successful and successfully easy to mix up. One describes a thing or result state. The other describes how an action happened.

Pattern four: after to

In a simple infinitive pattern, to is followed by the base form of a verb.

The company hopes to succeed in the new market.

The manager agreed to approve the request.

The team plans to complete the inspection by Friday.

Careful: Not every to works this way. Expressions such as look forward to seeing follow a different pattern. But in a simple infinitive pattern, to + base verb is a useful first check.

Pattern five: after a preposition

After prepositions such as with, for, of, by, and in, check whether the phrase needs a noun or noun phrase.

The board was impressed with the applicant’s decision.

The team was recognised for its performance.

The delay resulted in a formal complaint.

Fast check: if the blank follows a preposition and completes a phrase, check the thing or idea form first.

If choosing the preposition itself is the problem, review Part 5 Prepositions: In, At, On, By, With, To, For.

Common TOEIC word families

success familysucceed / success / successful / successfully
decision familydecide / decision / decisive / decisively
approval familyapprove / approval / approved / approving
application familyapply / application / applicant / applicable
performance familyperform / performance / performer
competition familycompete / competition / competitive / competitively

Small words around the blank matter

Word-family questions are not solved by vocabulary alone. Nearby words can signal the grammatical job of the blank.

The company’s recent ___ led to a major contract.

Signal: company’s recent ___ → a thing or idea.

Answer direction: success.

The company ___ completed the project.

Signal: completed → describes how the action happened.

Answer direction: successfully.

Quick TOEIC check

1. The marketing campaign was highly ___.

2. The team completed the installation ___.

3. All ___ must be submitted by Friday.

4. The manager will ___ the proposal tomorrow.

Fast-reader mistake

Under time pressure, it is easy to see familiar meaning and choose too quickly. For example, success, successful, and successfully all feel positive. But this kind of Part 5 item is not asking only about meaning. The grammatical job of the blank matters.

Bad shortcut: “This word has the right meaning.”

Better shortcut: “What job does the blank need to do?”

Why this mistake returns under pressure

Under time pressure, similar-looking words feel almost identical. An MTC quick-decision move is to delay the meaning check briefly and inspect the nearby signal first.

MTC quick-decision tool

Use this shortcut:

Needs a thing or idea → success / decision / application / performance

Describes a business thing → successful / decisive / applicable / competitive

Describes how an action happened → successfully / decisively / competitively

After will or simple to action pattern → succeed / decide / apply / approve

Final takeaway

TOEIC word-family questions are not just vocabulary questions. Nearby sentence signals can help you identify the required form.

Find the job of the blank, match the form, and move on.

Q1: What’s the difference between “success” and “successful”? A1: “Success” is a noun. “Successful” is an adjective. Example: She had great success. ✅ (noun) She is a successful person. ✅ (adjective) Q2: How do I know when to use a noun vs a verb? A2: Look at the grammar around the blank. After “the” or “a,” you usually need a noun. After “to,” you usually need a verb. Q3: What part of speech usually comes after a preposition like “with” or “by”? A3: A noun. Example: He was praised by the manager. → “manager” is a noun. Q4: What’s the trick to solving word family questions in Part 5? A4: Don’t guess based on word meaning. Look at the sentence structure. Eliminate options that don’t match the grammar role (verb, noun, etc). Q5: Is “decide” a noun or a verb? A5: “Decide” is a verb. The noun form is “decision.” Example: They will decide tomorrow. ✅ It was a difficult decision. ✅ Q6: What’s the adverb form of “successful”? A6: “Successfully.” Example: She successfully launched the product. Q7: Are word families common in TOEIC Part 5? A7: Yes — they appear in almost every test. TOEIC often gives you four options from the same family and tests your grammar knowledge, not just vocabulary. Q8: Can I just memorize which form is right? A8: Not reliably. TOEIC changes the sentence. You need to understand why a noun or verb fits based on the sentence pattern. Q9: What if two options seem possible? A9: Double-check what comes before and after the blank. That will tell you what part of speech is needed. Q10: Is it better to learn word families as groups? A10: Yes. Instead of learning words one by one, group them by form — verb, noun, adjective, adverb — and practice switching between them in full sentences.