The Basic Rule: One Verb Follows Another

In English, when you use two verbs together in a sentence, the first verb dictates the grammatical form of the second verb. While some verbs are followed by an -ing word (a gerund), a very large and important group of verbs must be followed by to + the infinitive (the base form of the verb).

Think of the first verb as the "boss." If the boss is a verb about planning, wanting, or promising, it almost always demands a to-infinitive right after it.

✅ I decided to bake a chocolate cake. ❌ I decided baking a chocolate cake.

Common Verbs That Demand a To-Infinitive

There is no single rule to guess every verb that takes an infinitive, but they often fall into a few logical categories. When you use these verbs, the action that follows is usually something that hasn't happened yet, or is focused on a future goal or choice:

• Plans and Intentions: plan, decide, aim, hope, attempt, want, try
• Promises and Agreements: promise, agree, refuse, offer
• Necessities and Learning: need, learn, fail

✅ We need to buy some snacks before the road trip. ❌ We need buy some snacks before the road trip.

✅ He always refuses to clean the bathroom. ❌ He always refuses cleaning the bathroom.

The Tricky Exception: Verbs That Change Meaning

A few special verbs can be followed by either a to-infinitive or an -ing verb, but the meaning of the sentence completely changes! The most common examples are forget, remember, and stop.

Let's look at forget, which often trips up learners:

• Forget + to-infinitive: You didn't do something because you forgot. (The forgetting happened before the action).
• Forget + -ing: You did something, but you lost the memory of doing it. (The action happened before the forgetting).

✅ I completely forgot to turn off the security cameras. (I didn't turn them off, and now the villain has a video of me!) ✅ I will never forget winning that championship. (I won it, and the memory will stay with me forever.)

A Common Error to Watch Out For

The most frequent mistake B1 and B2 learners make is dropping the word "to" completely, leaving two base verbs sitting awkwardly next to each other. In English, you generally cannot stack two base verbs together without a link.

✅ I promise to bring the secret gadgets this time. ❌ I promise bring the secret gadgets this time.

Another common trap is over-applying the -ing form because it feels natural or translates directly from your native language. Always double-check verbs of intention (like plan or decide). If you are talking about a goal, a promise, or a choice, you almost certainly need to plus the base verb.