Grammar Rule in 30 Seconds
Zero Conditional describes universal truths and facts, while First Conditional predicts specific future outcomes based on possible conditions.
- Use Zero for 'Always' facts: If you heat ice, it melts.
- Use First for 'Maybe' futures: If it rains, I will stay home.
- Zero uses Present + Present; First uses Present + Will.
Overview
If I stay up late, I am tired って言う人もいれば、 If I stay up late, I will be tired って言う人もいるんだろう？ ほんの些細な違いに聞こえるよね？ will というたった一語が、文全体の雰囲気をガラッと変えちゃうんだ。もし「どっちを使えばいいの？」って迷ったことがあるなら、ここはまさに君のための場所だよ。if を whenever に置き換えても意味が通じるなら、たぶん Zero Conditional が必要だね。もし特定の瞬間――待っているメールやプレイ中のゲームのような――について話しているなら、First Conditional が君の親友になるはず。それは 'I always get hungry at night' と言うのと、 'I will be hungry if I don't eat now' と言うのとの違いだね。How This Grammar Works
if か when で始まるよ。論理はシンプルで、「Aという事象」が「Bという事象」を引き起こす、というもの。I get a headache if I look at my screen too long （Zero）とも言えるし、 I will get a headache if I look at my screen for another hour （First）とも言える。if の部分が先に来るなら、カンマが必要。後に来るなら、カンマはいらない。句読点が君の代わりに仕事をしてくれているようなもんだね。
Formation Pattern
If the sun sets, it gets dark.
if 節では Present Simple を使い、結果の節では will + 動詞を使おう。
If the sun sets soon, I will go home.
If I will see her とは絶対に言わない。常に If I see her だよ。 will は結果の部分にしか属さないんだ。
will の代わりに、 can, might, should などの他の法助動詞も使えるよ。 If you finish your homework, you can play Valorant. （自分や友達を釣るのにいい方法だね）。
When To Use It
If you swipe left, you delete the message. 毎日のルーチンについて話す場合も Zero。 If I drink coffee after 4 PM, I don't sleep. これは自分や世界にとって「いつも」真実であることのためのものだよ。If you pay for the Uber, I'll buy the pizza. 誰かに失敗について警告するなら First。 If you don't save your progress, you will lose the game level. これは「現実的な可能性」の時制なんだ。テキストメッセージや週末の計画、あるいは遅いWi-Fiへの文句を言うのに最適だよ。「もしWi-Fiが速くならなかったら、叫んでやる！（If the Wi-Fi doesn't speed up, I'll scream!）」（特定の脅し、特定の時間だね）。
Common Mistakes
if の部分に will を入れてしまうこと。 If it will rain, I'll stay home は間違いだよ。未来について考えているから、脳は両方の部分を未来形にしたがるけど、英語はそのへん細かいんだ。 if の部分は現在形（Present）にしておこう。If you freeze water, it will turn to ice はネイティブスピーカーにはちょっと奇妙に聞こえる。だって毎回必ず起きることだからね。 If you freeze water, it turns to ice の方がベターだ。s にも気をつけて。 if 節でこれを忘れないように！ If he call me は If he calls me にすべきだね。小さな詳細だけど、これがB1レベルとC1レベルの差になるんだ。unless は if not を意味することを忘れないで。 I won't go unless you go は I won't go if you don't go と同じ意味だ。ちょっと「おしゃれ」だけど、話し言葉の英語ではとても一般的だよ。Contrast With Similar Patterns
If I win the lottery, I will buy a car. （チケットを持ってるし、チャンスはある！）。If I won the lottery, I would buy an island. （チケットさえ持ってないし、ただ夢見てるだけ）。Quick FAQ
Zero Conditional で if の代わりに when を使ってもいい？
いいよ！ Zero では、それらはほとんど同じ意味になる。 When it rains, I take the bus は If it rains, I take the bus と同じことだね。
First Conditional で when は使える？
注意して！ 未来の文で when を使うと、それが起こると100%確信している意味になっちゃうんだ。 When I get home, I'll call you は、間違いなく家に帰るという意味。 If I get home early, I'll call you は、遅くなるかもしれないという意味を含んでいるよ。
なんで 'Zero' って呼ばれるの？
結果について「ゼロ（zero）」の疑いしかないからだよ。事実だからね！
If I am late, I'll call you は正しい？
完璧に正しいよ。これは特定の状況に対する典型的な First Conditional の文だね。
will の代わりに may は使える？
もちろん。 If it rains, we may stay home は、 will を使った場合よりも確信度が低いことを意味するだけだよ。
Zero vs First Conditional Structure
| Type | If-Clause (Condition) | Result Clause | Meaning |
|---|---|---|---|
|
Zero
|
If + Present Simple
|
Present Simple
|
General Truth / Fact
|
|
First
|
If + Present Simple
|
Will + Base Verb
|
Possible Future Outcome
|
|
Zero (Neg)
|
If + Don't/Doesn't
|
Don't/Doesn't
|
General Negative Fact
|
|
First (Neg)
|
If + Don't/Doesn't
|
Won't + Base Verb
|
Future Negative Prediction
|
Common Contractions in First Conditional
| Full Form | Contraction | Example |
|---|---|---|
|
I will
|
I'll
|
I'll help you.
|
|
You will
|
You'll
|
You'll see.
|
|
He will
|
He'll
|
He'll arrive soon.
|
|
She will
|
She'll
|
She'll call back.
|
|
It will
|
It'll
|
It'll rain.
|
|
We will
|
We'll
|
We'll be there.
|
|
They will
|
They'll
|
They'll win.
|
|
Will not
|
Won't
|
I won't go.
|
Meanings
The Zero Conditional expresses general truths, scientific facts, or habits where the result is certain. The First Conditional expresses a real possibility in the future where the result depends on a specific condition.
Scientific/General Truths (Zero)
Used for laws of nature or things that are 100% certain every time the condition is met.
“If water reaches 100 degrees, it boils.”
“If you don't eat, you get hungry.”
Future Predictions (First)
Used for specific situations in the future that are likely to happen.
“If I see Sarah, I will tell her about the party.”
“If we don't hurry, we'll miss the train.”
Instructions and Rules (Zero)
Used to give commands or state rules that apply every time.
“If the alarm sounds, leave the building immediately.”
“If you are late, please enter through the back door.”
Negotiations and Promises (First)
Used to make deals or offer specific future rewards/consequences.
“If you finish your homework, I'll buy you an ice cream.”
“If you help me move, I'll pay for lunch.”
Reference Table
| 種類 | 条件 (If節) | 結果 (主節) | 確実性 | 時間 |
|---|---|---|---|---|
|
ゼロ条件文
|
Present Simple
|
Present Simple
|
常に真実 / 事実
|
いつでも / 一般的
|
|
一条件文
|
Present Simple
|
will + Base Verb
|
可能性 / 蓋然性
|
未来
|
|
ゼロ条件文 例
|
`If you heat water,`
|
`it boils.`
|
100%確実
|
いつも
|
|
一条件文 例
|
`If it rains tomorrow,`
|
`we will stay home.`
|
起こりそう / 可能性あり
|
特定の未来
|
フォーマル度スペクトル
Should you provide assistance, I would be most grateful. (Asking for a favor)
If you help me, I will be very happy. (Asking for a favor)
If you help out, I'll be stoked. (Asking for a favor)
Help me out and I'm good. (Asking for a favor)
条件文の種類：ゼロ条件文 vs. 一条件文
ゼロ条件文
- If + Present Simple 条件
- Present Simple 結果
- Universal Truths 事実
- Habits 日常
- Always True 確実
一条件文
- If + Present Simple 条件
- will + Base Verb 結果
- Future Possibilities 予測
- Specific Events 起こりうる結果
- Probable 可能性
ゼロ条件文 vs. 一条件文 スナップショット
どの条件文を使うべき？
その条件が起こったとき、結果は常に起こりますか？（事実、習慣、指示）
その条件は将来の現実的な可能性で、起こりそうな未来の結果がありますか？
条件文シナリオマッチ
ゼロ条件文の使用例
- • 科学的事実
- • 一般的な真実
- • 規則的な習慣
- • 指示
一条件文の使用例
- • 将来の予測
- • 可能性のある計画
- • 警告/アドバイス
- • 特定のシナリオ
レベル別の例文
If you heat water, it gets hot.
If I am hungry, I eat.
If it rains, I will use an umbrella.
If you go now, you will be on time.
If you don't study, you don't learn.
If the sun shines, we go to the beach.
If I see him, I will give him the book.
Will you help me if I have a problem?
If you press the red button, the machine stops immediately.
If I have enough money next year, I'll travel to Japan.
If you don't leave now, you'll miss your flight.
Does the computer turn off if you close the lid?
If a company ignores its customers, it eventually fails.
If the inflation rate continues to rise, the central bank will increase interest rates.
If you happen to see Mr. Jones, will you please ask him to call me?
If you don't mind, I'll take a look at those documents now.
If one considers the historical context, the decision makes perfect sense.
If the board approves the proposal, we shall commence operations in July.
If you should require further assistance, our team will be available 24/7.
If the experiment fails to yield results, the funding will likely be revoked.
If the theory holds water, it necessitates a complete paradigm shift.
If the treaty is ratified, it will herald a new era of diplomatic cooperation.
If you are to succeed in this industry, you must be prepared for long hours.
If the evidence is found to be tampered with, the case will be dismissed.
間違えやすい
Learners use 'when' for possibilities and 'if' for certainties.
Learners mix up likely futures with imaginary ones.
Using 'will' for a general habit.
よくある間違い
If it will rain, I stay home.
If it rains, I stay home.
If you heat ice, it will melt.
If you heat ice, it melts.
If he come, I am happy.
If he comes, I am happy.
If I see her, I tell her.
If I see her, I will tell her.
If I will have time, I'll call.
If I have time, I'll call.
If you don't study, you fail.
If you don't study, you will fail.
When it rains, I will stay home.
If it rains, I will stay home.
If I would see him, I'll tell him.
If I see him, I'll tell him.
If you will be late, call me.
If you are late, call me.
If the water boils, it will turn to steam.
If the water boils, it turns to steam.
If you should to need help, ask.
If you should need help, ask.
If the weather will permit, we'll go.
If the weather permits, we'll go.
文型パターン
If you ___, you ___.
If it ___, I will ___.
If I ___, I'll ___.
___ if ___.
Real World Usage
If you restart the router, the light turns green.
If I'm late, I'll text you.
If I am hired, I will work hard.
If the sauce thickens too much, add water.
If you have a liquid over 100ml, you can't take it.
If you buy two, we'll give you the third for free.
いつも vs. 未来で考える
if節に'will'は絶対ダメ！
「when」で練習してみよう
短縮形がカギ
結果を考えてみよう
Smart Tips
Check if you have used 'will' twice. If you have, delete the one after 'if'.
Replace 'if' with 'when' for Zero Conditional facts.
Use the Zero Conditional with an imperative (command) for clarity.
Use the First Conditional to show a clear benefit.
発音
Contraction of 'will'
In the First Conditional, 'will' is almost always contracted to ''ll' in spoken English.
The 'if' pause
There is usually a slight rising intonation at the end of the 'if' clause, followed by a tiny pause.
Conditional Rise-Fall
If you help me ↗, I'll help you ↘.
Shows the connection between condition and result.
暗記しよう
記憶術
Zero is for 'Zero doubt' (facts). First is for 'First time' (specific future events).
視覚的連想
Imagine a science textbook for the Zero Conditional (facts that never change). Imagine a weather forecast for the First Conditional (things that might happen tomorrow).
Rhyme
If it's always true, Zero is for you. If it's a future plan, First is the man.
Story
A scientist (Zero) says, 'If you mix these, it explodes.' A gambler (First) says, 'If I win this round, I will be rich.' The scientist deals in facts; the gambler deals in possibilities.
Word Web
チャレンジ
Write down three things that are always true about your morning routine (Zero) and three things you might do this weekend if the weather is good (First).
文化メモ
Brits often use 'should' in the if-clause to make a request sound more polite and less direct.
Americans are very direct with First Conditionals, especially in business negotiations.
Scientific papers exclusively use the Zero Conditional to state findings that are considered objective truths.
The conditional structure in English evolved from Old English 'gif' (if), which was used to set a hypothesis.
会話のきっかけ
What do you do if you can't sleep at night?
If you win the lottery tomorrow, what will be the first thing you buy?
What happens to your mood if the weather is grey and rainy?
If you have free time this evening, what will you watch on TV?
日記のテーマ
よくある間違い
Test Yourself
If you heat ice, it ___ (melt).
Find and fix the mistake:
If I will study hard, I will pass the exam.
Choose the correct sentence:
Translate into English: 'Si tienes tiempo, te ayudaré.'
Answer starts with: ["I...
Score: /4
練習問題
8 exercisesIf you ___ ice, it melts.
If it rains tomorrow, we ___ (not go) to the park.
Find and fix the mistake:
If I will see her, I'll tell her.
1. If you freeze water... | 2. If I win the race...
If I eat too much, I feel sick. (Change to a specific future plan for tonight)
A: Are you coming to the party? B: If I ___ my work, I'll be there.
In the Zero Conditional, you can often replace 'if' with 'when'.
'If you touch a fire, you get burned.'
Score: /8
Practice Bank
11 exercisesIf you don't wear a coat in winter, you ___ (get) cold.
When the sun will rise, the birds start to sing.
Choose the correct sentence:
Translate into English: 'Si estudias hoy, mañana podrás relajarte.'
Arrange these words into a sentence:
Match the 'if' clauses with the correct result clauses:
If you don't charge your phone, it ___ (run) out of battery.
Choose the correct sentence:
Arrange these words into a sentence:
If you want good grades, you will study hard.
Translate into English: 'Si hace sol, siempre vamos a la playa.'
Score: /11
よくある質問 (8)
In the Zero Conditional, yes. In the First Conditional, using 'when' means you are certain the event will happen, while 'if' means it's just a possibility.
This is a rule of English grammar. The 'if' clause already sets the time frame, so we use the present tense to represent the condition.
Yes! 'If it rains, I'm going to stay home' is perfectly natural and common.
That's usually a Zero Conditional. 'If you are tired, go to bed.'
Only if the 'if' clause comes first. If the result clause comes first, no comma: 'I'll help you if I can.'
Yes, use 'might' or 'could' if you are less certain about the result.
No, it's also for personal habits. 'If I'm stressed, I exercise.'
'Unless' means 'if not'. 'Unless it rains, we'll go' = 'If it doesn't rain, we'll go.'
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
Si + presente + presente/futuro
English uses 'will' for the first conditional, while Spanish uses the future tense ending.
Si + présent + présent/futur
French also forbids the future tense immediately after 'si'.
Wenn + Präsens + Präsens/Futur
German word order (verb-final) in the condition clause.
~tara / ~ba / ~nara
Japanese uses suffixes on verbs rather than separate 'if' words and 'will' auxiliaries.
In / Idha
Arabic distinguishes the 'certainty' of the condition with different starting words.
Ruguo... jiu...
No tense changes or 'will' equivalents are required in Chinese.
Learning Path
Prerequisites
Learn These First
関連動画
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