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（不定式）旁边。这是一个超级全能的工具，能让你说话听起来不像教科书，而更像个真人。不管你是要抱怨游戏卡顿，还是跟朋友说很高兴看到他们的 TikTok 火了，这个句型都是你的好帮手。它在你的情绪和周围发生的动作之间架起了一座桥梁。而且，相比每次发表意见都要造那种又长又笨拙的 that 从句，用这个顺口多了。to + verb 形式）连在一起。我们用它来描述某事有多容易或多难，我们对某个动作的感觉，或者评价某人的行为。把形容词想象成“调味料”，而不定式就是被调味的“动作”。如果你说 It is important，你朋友肯定还在等下文。It is important to charge your phone（给手机充电很重要）才算把话说完整了。这就像说 'I’m happy'（我很开心）和 'I’m happy to help you with that Zoom setup'（我很乐意帮你搞定 Zoom 设置）的区别。前者是一种普遍状态；后者是对某个动作的具体反应。这就像给你的情绪加了个 GPS 坐标，这样别人就知道你到底在对什么做出反应。没有这个句型，英语就像个出 bug 的 App——数据一大堆，但没法顺畅浏览。How This Grammar Works
I am happy to meet you。简单吧？形容词定下基调，不定式告诉我们这个基调是关于什么的。我们主要有两种用法。第一种，用 It 做形式主语（占位符）。这特别适合陈述普遍事实或观点，比如 It is hard to wake up early。这里的 It 其实没啥实意；它只是帮真正的信息把门撑开。第二种，用真实的人或物做主语：You are lucky to win that giveaway。这里，焦点直接在人身上。在这两种情况下，逻辑都是一样的：形容词 + to + 动词。这就像乐高积木，只有中间有 to，两块积木才能拼在一起。如果少了 to，整个结构崩得比廉价手机屏还快。
Formation Pattern
It is，具体指人用 I am / You are / She is。如果说的是过去或未来，就用 was 或 will be。
happy, surprised）、难度（easy, impossible）或评价（kind, wrong）的词。
to 和动词原形。这里千万别给动词加 -ing 或 -ed。这是带着 to 保镖的“裸”动词。
It (Subject) + is (Verb) + dangerous (Adjective) + to share (To-Infinitive) + your password.
for [someone]。It is easy for me to use this app.（对我来说用这个 App 很简单。）不过别太嗨了，在中间塞一大段话，不然听的人都忘了句子开头是啥了！
When To Use It
This game is fun to play。客气的时候可以用：I’m sorry to bother you。在社交媒体上回应新闻时可以用：I was shocked to hear the news。它也是描述任务或挑战的首选。如果你在上班，老板问起某个项目，你可以说 It’s simple to fix 或者 It’s too complex to explain right now。你还会听到它跟 enough 或 too 这类形容词连用。I’m too tired to scroll any further 或者 The coffee is hot enough to drink。基本上，只要你想把某种性质跟一个活动挂钩，找它准没错。这就是语言版的给动作“打标签”，标上某种感觉。记住，这是用来表达*观点*和*反应*的，不只是陈述干巴巴的事实。你不会说 'The sky is blue to look at'（天空看起来是蓝的），除非你想当个让人摸不着头脑的诗人。
Common Mistakes
-ing 形式，因为在其他语境下感觉很顺。你可能想说 'It is easy learning English,' 但这在系统里是个 Bug。正确写法：It is easy to learn English。另一个经典错误是完全忘了 to。I am happy see you 听起来像个坏掉的机器人。你需要那个 to 把碎片粘起来。还有，小心“丢失 It”的错误。在某些语言里，你可以直接用形容词开头。在英语里，我们需要那个占位符 It。别说 'Is hard to finish'; 要说 It is hard to finish。最后，别跟“形容词 + 介词”的句型搞混了。如果你说 I’m good at，就必须用 -ing（I’m good at gaming）。但如果你用 easy，就需要用不定式（It is easy to game on this PC）。搞混这俩就像试着用 USB-C 线给 iPhone（旧款）充电——根本插不进去。Contrast With Similar Patterns
interested 总是接 in + -ing。你是 interested in learning，而不是 'interested to learn'（虽然别人可能也能听懂）。但是，happy 或 ready 几乎总是接不定式：ready to go，happy to stay。另一个对比是 That 从句。你可以说 I’m surprised that you called，或者用我们的规则：I’m surprised to receive your call。不定式版本通常更紧凑，感觉更直接一点。当你要引入一个全新的主语和动词时，用 That 版本。当动作是主角时，用“不定式”版本。这就像在完整电影和 15 秒短片之间做选择——都能讲故事，但其中一个看（消化）起来快得多。Quick FAQ
我可以用任何形容词吗？
大部分可以！特别是那些描述感觉、难度或观点的词。
如果我想表达否定怎么办？
只要在 to 前面加个 not 就行。It’s important not to forget your keys.
都是！你在面试时能用（I’m eager to start），跟朋友也能用（It’s great to see you）。
我可以跟 'too' 一起用吗？
可以！Too + 形容词 + 不定式 意味着某事是不可能的或负面的。It’s too expensive to buy.
那 'enough' 呢？
用 形容词 + enough + 不定式。I’m old enough to decide for myself.
动词时态会改变不定式吗？
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
| 形容词 | 含义 | 例句 | 重点 |
|---|---|---|---|
|
Easy
|
容易的
|
It's `easy to learn` new words.
|
easy to learn
|
|
Hard
|
困难的
|
It was `hard to solve` the puzzle.
|
hard to solve
|
|
Important
|
重要的
|
It's `important to listen` carefully.
|
important to listen
|
|
Pleasant
|
令人愉快的
|
It's `pleasant to walk` in the park.
|
pleasant to walk
|
|
Impossible
|
不可能的
|
It's `impossible to predict` the future.
|
impossible to predict
|
|
Exciting
|
令人兴奋的
|
It's `exciting to start` a new project.
|
exciting to start
|
|
Glad
|
高兴的
|
I'm `glad to see` you again.
|
glad to see
|
正式程度
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)
形容词 + To-Infinitive：你的观点工具箱
常见形容词
- Easy Not difficult
- Hard Difficult
- Important Necessary
- Happy Pleased
常见不定式
- to do perform an action
- to understand grasp meaning
- to say speak words
- to go depart
主要模式
- It's easy to use Express general opinion
- She is happy to help Express personal feeling
作用
- 表达观点 How you feel about an action
- 描述特征 What an action is like
形容词后：To-Infinitive vs. Gerund
我应该用 '形容词 + To-Infinitive' 吗？
你是在对某个 '动作' 表达观点或感觉吗？
该动作是否跟在 'easy', 'hard', 'important', 'happy' 这类形容词后面？
喜欢 'To-Infinitive' 的形容词大集合
观点/特征
- • Easy
- • Hard
- • Difficult
- • Simple
- • Impossible
- • Possible
- • Good
- • Bad
- • Fun
- • Boring
- • Interesting
情绪/感觉
- • Happy
- • Glad
- • Sad
- • Pleased
- • Delighted
- • Excited
- • Surprised
- • Shocked
- • Upset
- • Angry
- • Disappointed
必要性/重要性
- • Important
- • Necessary
- • Essential
- • Crucial
- • Vital
- • Obligatory
按水平分级的例句
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.
容易混淆
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.
常见错误
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.
句型
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.
哪些形容词适用？
It was clever to say that.
小心 -ing 陷阱！
加上 "对谁来说"
for + 某人："It's difficult for me to understand."听起来更地道
It's + adjective + to-infinitive 能让你的英语听起来更像母语。比如约会迟到时说：It was wrong to be late.
不仅仅是 'It's'
This job is impossible to finish today.
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.
发音
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.
记住它
记忆技巧
Remember: 'Adjectives are the bridge, and TO is the glue.'
视觉联想
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
挑战
Write 5 sentences about your day using 'It is [adjective] to [verb]'. Example: 'It is nice to drink coffee.'
文化笔记
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.
对话开场白
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?
日记主题
常见错误
Test Yourself
Score: /4
练习题
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 exercisesScore: /12
常见问题 (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
相关视频
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