✏️ TOEIC Grammar Focus: When to Use “Doing” and When to Use “To Do”

Understanding the difference between gerunds (doing) and infinitives (to do) is essential if you want to score well on TOEIC Part 5 and Part 6. This grammar point shows up in questions where all four options seem grammatically possible — until you realize the verb pattern determines everything.

It’s not just about memorizing – it’s about knowing what follows the verb.

🔹 What Are Gerunds and Infinitives?

  • A gerund is a verb ending in -ing that acts like a noun.
    Example: Swimming is good exercise.

  • An infinitive is the base form of a verb with to.
    Example: She wants to swim every morning.

They both look like verbs, but they behave more like nouns — often as subjects or objects in a sentence.

🔸 TOEIC Trap 1: Verb Patterns

The most common trap on TOEIC? Choosing the wrong form after certain verbs.

Some verbs are followed by gerunds only:
✅ enjoy doing, avoid doing, suggest doing
❌ enjoy to do, avoid to do

Other verbs take infinitives only:
✅ decide to do, hope to do, promise to do
❌ decide doing, hope doing

Examples:

  • “She enjoys working with clients.” ✅

  • “He decided to cancel the order.” ✅
    TOEIC will often give you both forms in the answer choices.

🔸 TOEIC Trap 2: Verb + Object + Infinitive

Some verbs require an object before the infinitive. These are often tested in Part 5.

Examples:

  • “They encouraged him to apply.”

  • “The manager asked me to submit the report.”
    TOEIC likes to test this by removing the object or replacing it with a gerund.

❌ “They encouraged to apply.”
✅ “They encouraged him to apply.”

🔸 TOEIC Trap 3: Verbs That Take Both — With a Change in Meaning

Some verbs can be followed by either a gerund or an infinitive — but the meaning changes.

Examples:

  • “He stopped smoking.” = He quit the habit.

  • “He stopped to smoke.” = He paused another action in order to smoke.

Another one:

  • “I remember meeting her.” = I have a memory of it.

  • “I remember to meet her.” = I must not forget to do it.

These subtle differences are perfect for TOEIC test designers — and dangerous for rushed test-takers.

🔸 TOEIC Trap 4: Prepositions Take Gerunds

After a preposition, always use the -ing form.

Examples:

  • “She’s good at negotiating.”

  • “Before leaving, please lock the door.”

  • “They succeeded in winning the bid.”

❌ “She’s good at to negotiate.”
✅ “She’s good at negotiating.”

TOEIC will often slip “to” in as a preposition to confuse you.

🔸 TOEIC Strategy: How to Beat These Questions

✅ Step 1: Identify the main verb.
✅ Step 2: Ask — what normally follows this verb? Gerund? Infinitive? Object + Infinitive?
✅ Step 3: Look for clues — is there a preposition? Is the subject remembering something, or remembering to do something?

And most importantly…

✅ Step 4: Memorize the common verb patterns. TOEIC tests the same ones again and again.

🧠 High-Frequency TOEIC Verb Patterns — Just Learn These

These verbs show up again and again on the TOEIC. If you remember what kind of word comes after them — doing or to do — you’ll ace these questions every time.

✅ Verbs Usually Followed by “Doing” (the -ing form)

Use doing after these verbs. Always.

  • avoid doing → We avoided taking unnecessary risks.

  • enjoy doing → He enjoys working with numbers.

  • consider doing → They are considering expanding to Europe.

  • finish doing → I just finished reading the report.

  • suggest doing → She suggested meeting next week.

🧠 Rule: No “to” here. TOEIC often gives you “suggest to meet” — don’t fall for it.

✅ Verbs Usually Followed by “To Do”

Use to do after these verbs. No -ing allowed.

  • decide to do → He decided to cancel the trip.

  • expect to do → We expect to finish by Friday.

  • hope to do → I hope to join the team soon.

  • offer to do → She offered to help with the project.

  • plan to do → They plan to expand next year.

  • want to do → I want to improve my score.

🧠 TOEIC trap: You’ll often see “planning expanding” or “hoping joining” — both are wrong.

✅ Verbs Followed by [Someone] + To Do

These verbs need a person in between and then “to do.”

  • ask someone to do → She asked him to wait.

  • tell someone to do → They told me to call back.

  • remind someone to do → I reminded her to submit the form.

  • advise someone to do → He advised me to apply early.

  • encourage someone to do → They encouraged us to try again.

🧠 TOEIC trap: Watch for missing objects.
❌ “They encouraged to try again” = WRONG.
✅ “They encouraged us to try again” = RIGHT.

⚠️ Verbs That Change Meaning Depending on the Form

These are sneaky — both forms are correct, but the meaning changes.

  • stop doing = quit an action
    She stopped smoking.

  • stop to do = pause one action to do another
    She stopped to smoke.

  • remember doing = recall a past event
    I remember meeting him last year.

  • remember to do = don’t forget
    Remember to lock the door.

  • try doing = experiment with something
    Try restarting the app.

  • try to do = make an effort
    Try to finish today.

🧠 These are classic TOEIC traps. Read the sentence carefully — they test meaning, not just grammar.

🔍 EN FAQ: Doing vs To Do What’s the difference between “doing” and “to do”? “Doing” is usually a gerund (-ing noun), “to do” is an infinitive. The verb before determines which one is correct. Should I say “I enjoy working” or “I enjoy to work”? Say “I enjoy working.” “Enjoy” is always followed by the -ing form. Is it correct to say “I decided doing it”? No. Use “I decided to do it.” “Decide” is always followed by “to + verb.” Which is correct: “They suggested meeting” or “They suggested to meet”? “Suggested meeting” is correct. “Suggest” takes the -ing form, not “to do.” Why is “want doing” incorrect? “Want” is always followed by “to + verb.” The correct form is “want to do.” What comes after “plan” — to do or doing? Use “to do.” Example: “They plan to launch the service.” Can I say “He stopped to smoke” and “He stopped smoking”? Yes, both are correct but have different meanings. One means to pause, the other means to quit. What does “remember doing” mean? It means you have a memory of the past action. Example: “I remember meeting her.” When do I use “remember to do” instead? Use “remember to do” when you need to remind yourself to do something. Example: “Remember to call him.” Does “try doing” mean the same as “try to do”? No. “Try doing” means experiment with something. “Try to do” means make an effort. What follows a preposition — doing or to do? Always use the -ing form after a preposition. Example: “She’s interested in working here.” Is “She’s good at to speak English” correct? No. It should be “She’s good at speaking English.” Can both “to do” and “doing” be correct after a verb? Yes, but it depends on the verb. Example: “start doing” and “start to do” are often both OK. What’s the pattern after “ask”? Use “ask + person + to do.” Example: “They asked me to help.” What’s wrong with “They asked to help”? It’s missing the object. Correct version: “They asked me to help.” What does “stop doing” mean? It means to quit a habit or activity. Example: “He stopped drinking coffee.” How can I tell which verbs take “doing”? Some verbs just always take -ing: enjoy, avoid, consider, finish, suggest. How can I tell which verbs take “to do”? Memorize common ones: want, hope, plan, offer, expect, decide. What’s the structure for “encourage”? Use “encourage + person + to do.” Example: “She encouraged me to try again.” How can I learn which pattern to use in TOEIC? Focus on high-frequency verb patterns. Learn which verbs take doing, which take to do, and which need an object.