Introduction

In this unit you will learn how to use infinitives and participles to create more advanced sentence structures. These forms help you connect ideas smoothly, express purpose, describe reasons, and add extra information without repeating full clauses. When you control them, your English becomes more natural, more precise, and easier to follow.

Learning Objectives

Learning Objectives
By the end of this unit, you will be able to: use the to-infinitive and the -ing form after common verbs; use infinitives to express purpose and after adjectives; use present and past participles to add descriptive information; and avoid typical mistakes with meaning and form.

1) The infinitive: form and main uses

The infinitive is the base form of the verb. It can appear with to (the to-infinitive) or without to (the bare infinitive). At B1 level, the most useful patterns are: verb + to-infinitive, adjective + to-infinitive, and infinitive of purpose.

1.1 Verb + to-infinitive

Many verbs are followed by the to-infinitive. In these structures, the infinitive often expresses a plan, intention, or decision.

Examples: I decided to leave early. She hopes to find a better job. We agreed to meet at six.

Important concept
After some verbs, changing from the to-infinitive to the -ing form can change the meaning. Learning the pattern is not only grammar; it is also meaning.

1.2 Adjective + to-infinitive

We often use the to-infinitive after adjectives to explain feelings, reactions, or difficulty.

Examples: I’m happy to help. It’s hard to concentrate today. She was surprised to hear the news.

1.3 Infinitive of purpose

We use the to-infinitive to explain why someone does something. This is common in spoken and written English because it is direct and efficient.

Examples: I went to the pharmacy to buy some medicine. He studied all weekend to pass the exam. We called you to check if you were okay.

1.4 Bare infinitive (without to)

The bare infinitive is used after modal verbs and after certain verbs like make and let.

Examples: You must leave now. She can drive. They made me wait. Let him explain.

2) The -ing form: gerunds and common patterns

The -ing form can function like a noun (often called a gerund) or as part of a verb form (continuous tenses). In this unit, we focus on the -ing form after verbs and prepositions, because it helps you link actions and ideas naturally.

2.1 Verb + -ing

Some verbs are followed by the -ing form. These often describe likes/dislikes, habits, and activities.

Examples: I enjoy reading in the evening. She finished writing the report. They suggested taking a taxi.

2.2 -ing after prepositions

After a preposition, we use the -ing form (not the infinitive). This includes common phrases with about, of, for, in, without, and before/after.

Examples: Thanks for coming. I’m interested in learning French. He left without saying goodbye. After finishing work, I went home.

Warning
Do not use to + verb after a preposition. Say: “I’m interested in learning,” not “interested in to learn.”

3) Participles: present and past participles as descriptions

Participles help you add information without starting a new sentence. They are very common in descriptions, stories, and explanations.

3.1 Present participle (-ing) to describe the cause or an active meaning

The present participle can describe something that is happening or a quality that “acts” on someone.

Examples: The film was exciting. (The film causes excitement.) I heard a crying baby. (The baby is crying.)

3.2 Past participle (-ed / irregular) to describe a result or passive meaning

The past participle often describes how someone feels, or a state that is the result of something.

Examples: I was excited about the trip. (I felt excitement.) We stayed in a crowded hotel. The documents are signed.

3.3 Participle clauses (B1 step)

You can use participles to create shorter clauses that add extra information. These clauses often share the same subject as the main clause.

Examples: Walking home, I met an old friend. (= While I was walking home, I met an old friend.) Shocked by the result, she called her teacher. (= Because she was shocked, she called her teacher.)

Important concept
In participle clauses, the subject should usually be the same as the subject of the main clause. This keeps the meaning clear and avoids confusing “floating” participles.

4) Infinitive vs -ing: meaning differences with common verbs

Some verbs can be followed by either the to-infinitive or the -ing form, but the meaning changes. At B1, focus on these useful contrasts.

4.1 Stop

Stop + -ing means you stop the activity. Stop + to-infinitive means you stop another action in order to do something else.

Examples: He stopped smoking. (He quit the activity.) She stopped to answer the phone. (She paused another action to answer.)

4.2 Remember / forget

Remember/forget + to-infinitive refers to remembering/forgetting a duty. Remember/forget + -ing refers to memories of the past.

Examples: Remember to lock the door. I’ll never forget meeting her for the first time.

4.3 Try

Try + to-infinitive means make an effort. Try + -ing means experiment with a possible solution.

Examples: I tried to call you, but there was no signal. Try restarting your computer.

Practice

Practice section
Complete each sentence with the correct form: to-infinitive, bare infinitive, -ing form, present participle, or past participle.