Grammar Rule in 30 Seconds
Use 'to' + verb after adjectives to describe an action, express feelings, or give opinions about a task.
- Use 'to' after adjectives of difficulty like 'easy' or 'hard' (It's easy to learn).
- Use 'to' after adjectives of emotion like 'happy' or 'sad' (I'm happy to help).
- Add 'not' before 'to' for negative sentences (It's important not to forget).
Overview
to-infinitive のすぐ隣にくっつけるだけ。これは、教科書っぽさを消して、もっと人間味のある話し方ができる超万能なツールの一つなんだ。ラグいゲームに文句を言っている時でも、友達のTikTokがバズって嬉しいと伝える時でも、このパターンは親友みたいな存在になるよ。自分の感情と、周りで起きている行動との間のギャップを埋めてくれるんだ。それに、意見があるたびに that 節を使って長くて不格好な文を作ろうとするより、ずっとスムーズだよ。to + verb form). We use it to describe how easy or difficult something is, how we feel about an action, or to judge someone's behavior.It is important, your friend is waiting for the rest. It is important to charge your phone completes the thought.How This Grammar Works
I am happy to meet you. Simple, right?It is hard to wake up early. The 'It' doesn't really mean anything; it’s just holding the door open for the real information. Second, we use a real person or thing as the subject: You are lucky to win that giveaway.to + Verb. It’s like a LEGO set where the pieces only click together if the to is in the middle.to, the whole structure falls apart faster than a cheap phone screen.
Formation Pattern
It is for general statements or I am / You are / She is for specific people. Use was or will be if you’re talking about the past or future.
happy, surprised), a difficulty level (easy, impossible), or a judgment (kind, wrong).
to plus the base form of the verb. Do NOT add -ing or -ed to the verb here. It’s the 'naked' verb with its to bodyguard.
It (Subject) + is (Verb) + dangerous (Adjective) + to share (To-Infinitive) + your password.
for [someone] before the infinitive. It is easy for me to use this app. Just don't get too carried away and add a whole paragraph in the middle, or your listener will forget how the sentence started!
When To Use It
This game is fun to play. Use it when you’re being polite: I’m sorry to bother you.I was shocked to hear the news. It’s also the go-to choice for describing tasks or challenges. If you’re at work and your boss asks about a project, you might say It’s simple to fix or It’s too complex to explain right now.enough or too. I’m too tired to scroll any further or The coffee is hot enough to drink. Basically, any time you want to link a quality to an activity, this is your guy.
Common Mistakes
-ing form because it feels natural in other contexts. You might want to say 'It is easy learning English,' but that’s a bug in the system. Correct: It is easy to learn English. Another classic mistake is forgetting the to entirely. I am happy see you sounds like a broken robot. You need that to to glue the pieces together. Also, watch out for the 'Missing It' error. In some languages, you can start with the adjective. In English, we need that placeholder It. Don't say 'Is hard to finish'; say It is hard to finish. Lastly, don't confuse this with the 'Adjective + Preposition' pattern. If you say I’m good at, you must use -ing (I’m good at gaming). But if you use easy, you need the infinitive (It is easy to game on this PC). Mixing these up is like trying to charge an iPhone with a USB-C cable—it just won't click.Contrast With Similar Patterns
interested always takes in + -ing. You are interested in learning, not 'interested to learn' (though people might still understand you). However, happy or ready almost always take the infinitive: ready to go, happy to stay.I’m surprised that you called, or you could use our rule: I’m surprised to receive your call. The infinitive version is usually tighter and feels a bit more immediate.Quick FAQ
Can I use this with any adjective?
Mostly, yes! Especially ones that describe feelings, difficulty, or opinions.
What if I want to make it negative?
Just put not before the to. It’s important not to forget your keys.
Is it formal or informal?
It’s both! You’ll use it in a job interview (I’m eager to start) and with friends (It’s great to see you).
Can I use 'too' with this?
Yes! Too + Adjective + Infinitive means something is impossible or negative. It’s too expensive to buy.
What about 'enough'?
Use Adjective + enough + Infinitive. I’m old enough to decide for myself.
Does the verb tense change the infinitive?
Nope! The infinitive stays the same whether it’s I was happy to help or I will be happy to help. The 'to' part is a time-traveler that never changes clothes.
Common Adjective + To-Infinitive Patterns
| Subject | Verb 'Be' | Adjective | Infinitive (to + verb) | Example |
|---|---|---|---|---|
|
It
|
is
|
easy
|
to learn
|
It is easy to learn.
|
|
I
|
am
|
happy
|
to help
|
I am happy to help.
|
|
They
|
were
|
surprised
|
to see
|
They were surprised to see us.
|
|
It
|
is
|
important
|
not to go
|
It is important not to go.
|
|
She
|
is
|
ready
|
to start
|
She is ready to start.
|
|
It
|
was
|
kind
|
to say
|
It was kind to say that.
|
Contractions in this Structure
| Full Form | Contraction | Usage |
|---|---|---|
|
It is easy
|
It's easy
|
Very common in speech
|
|
I am happy
|
I'm happy
|
Standard informal/neutral
|
|
It was not easy
|
It wasn't easy
|
Common in past tense
|
Meanings
This structure is used to provide more information about an adjective by following it with an infinitive verb. It often describes the difficulty, emotion, or necessity associated with an action.
Difficulty and Ease
Describing how hard or easy an action is to perform.
“It's hard to breathe in this heat.”
“The instructions were simple to follow.”
Emotional Reaction
Expressing how someone feels about doing something.
“I'm delighted to meet you.”
“She was surprised to see him there.”
Judgment and Character
Commenting on someone's behavior or character traits.
“It was kind of you to help.”
“It's rude to interrupt people.”
Necessity and Importance
Stating that an action is required or vital.
“It's important to arrive on time.”
“It is necessary to sign the form.”
Reference Table
| 形容詞 | 意味 | 例文 | 注目ポイント |
|---|---|---|---|
|
Easy
|
難しくない、簡単な
|
It's `easy to learn` new words.
|
easy to learn
|
|
Hard
|
難しい、骨の折れる
|
It was `hard to solve` the puzzle.
|
hard to solve
|
|
Important
|
重要な、必要な
|
It's `important to listen` carefully.
|
important to listen
|
|
Pleasant
|
楽しい、気持ちいい
|
It's `pleasant to walk` in the park.
|
pleasant to walk
|
|
Impossible
|
不可能、できない
|
It's `impossible to predict` the future.
|
impossible to predict
|
|
Exciting
|
ワクワクする、刺激的な
|
It's `exciting to start` a new project.
|
exciting to start
|
|
Glad
|
嬉しい、喜ばしい
|
I'm `glad to see` you again.
|
glad to see
|
フォーマル度スペクトル
It is quite straightforward to complete the application. (Completing a task)
It's easy to finish the form. (Completing a task)
It's a breeze to do. (Completing a task)
It's a piece of cake to knock out. (Completing a task)
形容詞 + to不定詞：あなたの意見ツールキット
よく使う形容詞
- Easy 難しくない
- Hard 難しい
- Important 必要な
- Happy 嬉しい
よく使う不定詞
- to do 行動する
- to understand 意味を理解する
- to say 言葉を話す
- to go 出発する
主要なパターン
- It's easy to use 一般的な意見を表現する
- She is happy to help 個人的な感情を表現する
何をするか
- Express Opinions 行動についてどう感じるか
- Describe Characteristics 行動がどんなものか説明する
形容詞の後の to不定詞 vs. 動名詞
「形容詞 + to不定詞」を使うべき？
行動について意見や感情を表現していますか？
Does the action follow an adjective like 'easy', 'hard', 'important', 'happy'?
to不定詞が大好きな形容詞たち
意見・特徴
- • Easy
- • Hard
- • Difficult
- • Simple
- • Impossible
- • Possible
- • Good
- • Bad
- • Fun
- • Boring
- • Interesting
感情・気持ち
- • Happy
- • Glad
- • Sad
- • Pleased
- • Delighted
- • Excited
- • Surprised
- • Shocked
- • Upset
- • Angry
- • Disappointed
必要性・重要性
- • Important
- • Necessary
- • Essential
- • Crucial
- • Vital
- • Obligatory
レベル別の例文
I am happy to help you.
It is good to see you.
It is easy to read this.
She is sad to go.
It is important to drink water.
It is not easy to learn Chinese.
Are you ready to order?
It is dangerous to swim here.
It is difficult for me to speak in public.
It was very kind of you to invite us.
It is necessary to wear a helmet.
I was surprised to find the door open.
The results are likely to be positive.
It is vital not to underestimate the competition.
He is always the first to arrive at work.
The instructions are too complicated to follow.
It is imperative to address these issues immediately.
She was relieved to have finished the marathon.
It is quite common for students to feel overwhelmed.
The book is well worth the effort to read.
It is incumbent upon the board to ensure transparency.
The theory is far too abstract to be applied practically.
He was loath to admit that he had been mistaken.
It is seldom easy to reconcile such disparate views.
間違えやすい
Learners often use 'to' when a specific preposition is required by the adjective.
Both 'Learning is fun' and 'It is fun to learn' are correct, leading to choice paralysis.
Learners forget the 'to' after enough/too.
よくある間違い
It is easy learn.
It is easy to learn.
I am happy for see you.
I am happy to see you.
It is good to seeing you.
It is good to see you.
Is easy to go.
It is easy to go.
It is important to not forget.
It is important not to forget.
The book is easy for read.
The book is easy to read.
I am ready for go.
I am ready to go.
It is easy for me learning.
It is easy for me to learn.
It was kind for you to help.
It was kind of you to help.
I am sorry to being late.
I am sorry to be late.
It is easy that I learn.
It is easy for me to learn.
文型パターン
It is ___ to ___.
I am ___ to ___.
It is ___ for ___ to ___.
It was ___ of ___ to ___.
Real World Usage
It's great to hear from you!
I am eager to learn new skills.
It's easy to get lost in this city.
It's important to leave a note for the driver.
So happy to share this news!
It's necessary to take this twice a day.
これに合う形容詞の種類！
動名詞 vs. 不定詞の落とし穴
「誰にとって」を追加する時
自然な英語に聞こえる魔法！
「It's」だけじゃない使い方
Smart Tips
Start your sentence with 'It's better to...' or 'It's important to...'. It sounds much more polite than a direct command.
Use the 'for [person]' bridge right after the adjective.
Always place 'not' as a guard in front of 'to'.
Switch 'for' to 'of' to sound more native when talking about someone's character.
発音
The 'to' reduction
In natural speech, 'to' is often reduced to a weak 'tuh' /tə/.
Linking 'is' and 'easy'
The 's' in 'is' links to the 'e' in 'easy', sounding like /ɪzi/.
Emphasis on the Adjective
It's EASY to learn. (Stress on EASY)
Emphasizing the quality of the action.
暗記しよう
記憶術
Remember: 'Adjectives are the bridge, and TO is the glue.'
視覚的連想
Imagine a bridge connecting a 'Happy Face' (Adjective) to a 'Running Man' (Verb). The bridge is labeled 'TO'.
Rhyme
When an adjective is in your view, follow it up with 'to' and do!
Story
A man named 'It' was very 'Happy'. He wanted 'to help' his friend. He found it 'easy to carry' the bags, but 'hard to walk' up the stairs.
Word Web
チャレンジ
Write 5 sentences about your day using 'It is [adjective] to [verb]'. Example: 'It is nice to drink coffee.'
文化メモ
British speakers frequently use 'It's kind of you to...' as a polite way to say thank you or accept a gift.
American English often uses 'It's important to...' in business settings to be direct but professional.
This structure is preferred in international business because it is clear and avoids the ambiguity of some gerund phrases.
The 'to' particle in English originally indicated direction (like 'towards'). Over time, it became a marker for the infinitive verb.
会話のきっかけ
Is it easy to find good food in your city?
What is the most important thing to do for a healthy life?
Were you surprised to see how much technology has changed?
Is it rude to use your phone at the dinner table?
日記のテーマ
よくある間違い
Test Yourself
It's so important ___ your friends.
Find and fix the mistake:
The book was difficult understanding.
Choose the correct sentence:
Translate into English: 'Es emocionante viajar a nuevos lugares.'
Answer starts with: ["I...
Score: /4
練習問題
8 exercisesIt is important ___ (brush) your teeth every day.
Find and fix the mistake:
It is difficult for me learning English grammar.
Which sentence is correct?
not / to / important / it / is / forget / .
How do you say this in English?
Match: 1. Happy, 2. Hard, 3. Ready
A: 'I'm so nervous about the test.' B: 'Don't worry, it's ___.'
Identify the incorrect sentence.
Score: /8
Practice Bank
12 exercisesIt's often challenging ___ focused during long lectures.
I'm happy helping you with your project.
Choose the correct sentence:
Translate into English: 'Es imposible terminar esto hoy.'
Arrange these words into a sentence:
Match the adjectives with the correct action:
The movie was thrilling ___ from start to finish.
It's too late starting now.
Which sentence is correct?
Translate into English: 'Fue amable de tu parte invitarme.'
Arrange these words into a sentence:
Match the emotions with what they relate to:
Score: /12
よくある質問 (8)
Yes, both are correct. However, `It is easy to learn` is much more common in spoken English because it emphasizes the adjective first.
We use `of` when the adjective describes the person's character (kind, mean, brave). We use `for` when the adjective describes the difficulty or effect of the action (hard, easy, important).
In casual speech, people say this often. However, in formal writing, you should put `not` before `to`: 'It's important not to forget.'
Most adjectives work, especially those describing difficulty, emotions, or opinions. However, some adjectives like `interested` or `afraid` often prefer a preposition + gerund (afraid of falling).
If you aren't using a person as the subject (like 'I am happy'), then yes, English requires the 'dummy' subject `It`.
Just change the verb 'be' to the past tense: `It was easy to learn` or `I was happy to help.` The infinitive part (`to learn`) stays the same.
Yes! This is a common extension: `It is too hot to eat` or `He is old enough to drive.`
It is neutral. It is used in both very formal academic writing and very casual text messages.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
Es fácil de [verbo]
Spanish uses 'de' or 'para' instead of 'to'.
C'est facile à [verbo]
French has two different particles (à/de) while English mostly uses 'to'.
Es ist leicht zu [verbo]
The 'zu' in German often comes at the very end of the clause.
[Verb] no wa kantan desu
Japanese uses nominalization particles instead of an infinitive marker.
Min al-sahli an [verb]
Arabic uses a 'that' (an) conjunction rather than a 'to' particle.
Hen rongyi [verb]
Chinese has no infinitive marker or 'dummy' subject.
Learning Path
Prerequisites
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How to use GERUNDS and INFINITIVES | Confusing English Grammar
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GERUND (ing) or INFINITIVE (to) – Everything You Need to Know!
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