The Fascinating Relationship Between Adjectives and Infinitives: A Complete Grammar Guide

Introduction

In English grammar, the combination of adjectives + infinitives (e.g., happy to help, difficult to understand) creates powerful and expressive structures. These constructions allow for nuanced meaning and are essential for fluent communication.

This guide explores:

✔ How adjectives pair with infinitives

✔ Common adjective + infinitive patterns

✔ Special cases and exceptions

✔ Practical examples for natural usage

What Are Adjective + Infinitive Constructions?

An adjective + infinitive structure occurs when an adjective modifies a subject and is followed by an infinitive verb (to + base form). These constructions often describe:

Emotions (happy to see you)

Difficulty or ease (hard to believe)

Necessity or obligation (important to remember)

Basic Structure:

[Subject] + [Linking Verb] + [Adjective] + [Infinitive]

She was happy to help.

This problem is difficult to solve.

Common Types of Adjective + Infinitive Combinations

1. Adjectives Showing Emotion or Attitude

These describe how someone feels about an action.

Examples:

I’m glad to meet you.

He was surprised to hear the news.

They were excited to travel.

Common Adjectives:

✔ Happy, glad, sad, surprised, excited, afraid, anxious, eager, reluctant

2. Adjectives Indicating Difficulty or Ease

These describe how easy or hard an action is.

Examples:

English is easy to learn.

The instructions were hard to follow.

This puzzle is impossible to solve.

Common Adjectives:

✔ Easy, difficult, hard, simple, impossible, tough, challenging

3. Adjectives Expressing Necessity or Importance

These highlight obligation or significance.

Examples:

It’s important to drink water.

She is likely to win.

You are free to leave anytime.

Common Adjectives:

✔ Important, necessary, essential, likely, certain, free, ready

Special Cases & Advanced Usage

1. "It" as a Dummy Subject

When the real subject is an infinitive, we often use "It" as a placeholder.

Examples:

It’s nice to see you. (Instead of "To see you is nice.")

It was foolish to ignore the warning.

2. Passive Infinitive Structures

Sometimes, a passive infinitive (to be + past participle) is used.

Examples:

The document is confidential and not allowed to be shared.

This fruit is safe to be eaten.

3. Adjectives That Require an Infinitive

Some adjectives must be followed by an infinitive.

Examples:

He was bound to fail. (❌ Not: "He was bound failing.")

She is certain to succeed.

Common Mandatory Adjectives:

✔ Bound, certain, due, likely, unlikely, sure

Common Mistakes to Avoid

❌ Incorrect: I’m boring to read this book.

✅ Correct: I’m bored to read this book. (Boring describes things, bored describes people.)

❌ Incorrect: She is easy to working with.

✅ Correct: She is easy to work with. (Use base verb after to.)

❌ Incorrect: It’s dangerous driving at night.

✅ Correct: It’s dangerous to drive at night. (Infinitive needed after dangerous.)

Why Are Adjective + Infinitive Structures Important?

✔ Make sentences more natural (Native speakers use them frequently).

✔ Add emotional depth (happy to help vs. helps willingly).

✔ Clarify necessity or difficulty (hard to solve vs. a difficult problem).

Conclusion

Mastering adjective + infinitive structures enhances fluency and expressiveness in English. Key takeaways:

Emotion adjectives (happy, surprised) often pair with infinitives.

Difficulty adjectives (easy, hard) describe how challenging an action is.

Some adjectives require infinitives (bound, certain).

Avoid common errors (wrong adjective form, incorrect verb tense).

Practice by identifying these structures in books, movies, and conversations!