B1 · 中級 チャプター 17

Expressing Degrees of Certainty

3 トータルルール
36 例文
5 分
このチャプターのルール クイック練習

Chapter in 30 Seconds

Move beyond simple 'will' to express advice, permission, and varying levels of possibility.

  • Replace 'will' with modals like 'should' to give conditional advice.
  • Use 'might' and 'may' to express uncertain future outcomes.
  • Apply 'can' to describe potential abilities or granted permissions.
Master the spectrum of certainty in your future plans.

学べること

Want to share how likely something is, or offer advice for the future? Dive into this chapter and discover how to use the First Conditional with words like 'maybe' and 'should' to express different certainties. You'll be predicting and advising with confidence!

Learning Objectives

By the end of this chapter, you will be able to:

  1. 1
    By the end you will be able to provide conditional advice using 'should' in the main clause.
  2. 2
    By the end you will be able to distinguish between certain and uncertain outcomes using 'might' and 'may'.
  3. 3
    By the end you will be able to offer permission or describe future abilities based on specific conditions.

チャプターガイド

Overview

Mastering how to talk about possibilities and give advice is a crucial step in sounding more natural and confident in English. At the B1 English grammar level, you're ready to move beyond simple predictions and start sharing how likely something truly is, or offering nuanced suggestions for the future. This chapter focuses on expressing degrees of certainty using the versatile First Conditional.
Instead of always saying will, we'll explore how words like 'can', 'might', and 'should' allow you to convey everything from a strong recommendation to a tentative guess. You’ll learn how to predict outcomes with different levels of confidence and give advice effectively, preparing you for a wider range of real-world conversations and making your English sound much more sophisticated and precise. Get ready to predict and advise like a pro!

How This Grammar Works

At its heart, the First Conditional structure is
If [condition], then [result].
Typically, we use will in the result clause (e.g.,
If it rains, I will stay home.
). However, to express different degrees of certainty or add more specific meanings like advice or ability, we can swap will for various modal verbs or probability adverbs.
When you want to express a *possible, but uncertain* future result, you can use 'may' or 'might' instead of 'will'. For example:
If I finish work early, I may go to the gym
or
If she calls, I might answer.
Both 'may' and 'might' signal that the outcome isn't guaranteed – it's just a possibility. We can also use adverbs like 'maybe' or 'probably' with 'will' to achieve a similar effect of reduced certainty: "If I have time, I'll maybe visit you or If the weather is good, we'll probably go to the beach." These adverbs often sound a bit more casual.
Using 'can' in the result clause of a First Conditional sentence adds another layer of meaning. It can indicate a future possibility or ability that depends on the condition:
If you study hard, you can pass the exam
(ability). It can also convey permission:
If you finish your homework, you can watch TV
(permission).
So, 'can' is perfect for when the condition enables an action.
Finally, swapping 'will' for 'should' transforms the result into a recommendation or advice.
If you feel unwell, you should see a doctor.
Here, 'should' makes the result clause an advisable action rather than a simple prediction. By mastering these small changes, you can convey a much richer spectrum of meaning in your future predictions and advice.

Common Mistakes

Here are some common pitfalls when expressing degrees of certainty with the First Conditional:
  1. 1✗ If it will rain, I might stay home.
✓ If it rains, I might stay home.
*Explanation:* Remember, the 'if' clause in the First Conditional uses the present simple tense, not future. The modal verb (like 'might') goes in the result clause.
  1. 1✗ If I finish early, I probably will go.
✓ If I finish early, I will probably go. OR If I finish early, I 'll probably go.
*Explanation:* When using adverbs like 'probably' or 'maybe' with 'will', they usually come *between* 'will' and the main verb, or after the contraction 'll.
  1. 1✗ If you study, you can pass better.
✓ If you study, you can pass the exam.
*Explanation:* 'Can' expresses ability or permission; it doesn't modify the *quality* of passing. Ensure 'can' is used correctly for what is possible or allowed.

Real Conversations

A

A

If you don't hear from me by 6 PM, I might be stuck in traffic.
B

B

Okay, I'll call you then. If you can't make it, just send a quick text.
A

A

I'm not sure what to do about my presentation.
B

B

If you practice more, you should feel more confident. If you still struggle, maybe I can help you rehearse.
A

A

Do you think we'll finish this project on time?
B

B

If everyone cooperates, we can definitely get it done. But if we encounter any unexpected problems, we may need an extension.

Quick FAQ

Q

What's the difference between

If it rains, I will stay home
and
If it rains, I might stay home
?

Will implies you are certain about your action if the condition is met. Might suggests there's a possibility you'll stay home, but it's not guaranteed. You're expressing a lower degree of certainty with might.

Q

Can I use maybe or probably with might or may?

While grammatically possible (e.g.,

If it rains, I might maybe stay home
), it's often redundant and sounds less natural. Stick to one way of showing probability for clarity: either will probably or just might/may.

Q

Is can in the First Conditional always about ability?

No, 'can' can also express permission (

If you finish your dinner, you can have dessert
) or future possibility (
If the store is open, you can buy milk there
). The context usually makes the meaning clear.

Cultural Context

Native English speakers often use these variations to soften direct statements or appear less assertive, especially when giving advice or making predictions. For instance,
You should do this
is advice, but
If you have time, you could do this
is a gentler suggestion. In informal speech, you might hear "If I see him, I'll maybe tell him" which is very common.
The choice of modal can subtly reflect politeness, confidence, or hesitancy, making communication more nuanced and natural.

重要な例文 (6)

1

If you study hard, you `can` pass the exam easily.

一生懸命勉強すれば、簡単に試験に合格できますよ。

第一条件文：助動詞（can, might, should）の使い方
2

If it rains tomorrow, we `might` stay home and watch movies.

もし明日雨が降ったら、家にいて映画を見るかもしれません。

第一条件文：助動詞（can, might, should）の使い方
3

If you don't hydrate enough, you `will probably` feel tired later.

十分な水分補給をしないと、後でたぶん疲れるでしょう。

第一条件文：多分/おそらく (May/Might)
4

If the concert sells out quickly, we `may` not get tickets.

もしコンサートがすぐに売り切れたら、チケットが取れないかもしれません。

第一条件文：多分/おそらく (May/Might)
5

If it rains, we can stay inside and play games.

もし雨が降ったら、私たちは家の中にいてゲームができます。

Can を伴う仮定法第一形 (未来の可能性と許可)
6

You can borrow my book if you promise to return it.

もし返すと約束するなら、私の本を借りてもいいですよ。

Can を伴う仮定法第一形 (未来の可能性と許可)

ヒントとコツ (3)

💡

変化をつけよう！

「First Conditional」では、「will」だけを使うのではなく、「can」「might」「should」を使うと、文にもっと多くの情報や正確さを加えられます。可能性やアドバイスの微妙な違いを理解していることが伝わるんですよ。
If you practice, you can improve.
frontend.learn_grammar.from_rule: 第一条件文：助動詞（can, might, should）の使い方
💡

確実性の度合いを測ろう

結果に対する確信度合いによって、「will probably」（より確実）と「may/might」（あまり確実ではない）を使い分けましょう。あなたの正確な確信レベルを表現することが大切です！ "If there's no traffic, I will probably arrive on time."
frontend.learn_grammar.from_rule: 第一条件文：多分/おそらく (May/Might)
💡

現実的な可能性を見極めよう

「can」を使う仮定法第一文型は、現実的で起こりそうなことについて話す時に使います。夢物語には使いませんよ！「If I study hard, I can pass the exam.」
frontend.learn_grammar.from_rule: Can を伴う仮定法第一形 (未来の可能性と許可)

重要な語彙 (6)

probability the extent to which something is likely to happen outcome the result or consequence of an action permission the act of allowing someone to do something advice guidance or recommendations offered with regard to prudent future action certainty the state of being completely confident or sure of something condition something that must happen or be true before something else can happen

Real-World Preview

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A Weekend Trip Plan

Review Summary

  • If + Present Simple, [Subject] + should/might/can + Verb

よくある間違い

You cannot use 'will' and 'might' together. 'Might' already implies a future possibility.

Wrong: If it rains, I will might stay home.
正解: If it rains, I might stay home.

Modal verbs like 'should' replace 'will' entirely in the result clause of a conditional.

Wrong: If you are tired, you will should rest.
正解: If you are tired, you should rest.

In English, 'will can' is ungrammatical. Use 'can' for the conditional result or 'will be able to'.

Wrong: If I study hard, I will can speak English.
正解: If I study hard, I can speak English (or 'I will be able to speak').

Next Steps

You're making incredible progress! By mastering these nuances, you're sounding much more like a fluent English speaker. Keep it up!

Write 3 'If' sentences giving advice to a tourist in your city.

Record yourself explaining three things you might do if you win the lottery.

Continue to: Getting Started with the Present Perfect

クイック練習 (8)

助動詞を使った「First Conditional」を正しく使っている文を選びましょう。

Choose the correct sentence:

✓ Correct! ✗ Not quite. Correct answer: If he's hungry, he should eat something.
「should」のような助動詞の後には、動詞の原形（toのない不定詞）を使わなければなりません。また、「if」節も正しく現在形（'he's hungry'）を使っています。

frontend.learn_grammar.from_rule: 第一条件文：助動詞（can, might, should）の使い方

文中の間違いを見つけて修正しましょう。

Find and fix the mistake:

If she will arrive late, we might start dinner without her.

✓ Correct! ✗ Not quite. Correct answer: If she arrives late, we might start dinner without her.
「First Conditional」の「if」節は現在形を使わなければなりません。未来の可能性の場合、「if」節には「will」を使いません。

frontend.learn_grammar.from_rule: 第一条件文：助動詞（can, might, should）の使い方

文中の間違いを見つけて修正しましょう。

Find and fix the mistake:

If it will rain tomorrow, we can stay inside.

✓ Correct! ✗ Not quite. Correct answer: If it rains tomorrow, we can stay inside.
仮定法第一文型の「if」節は常に現在形を使い、「will」は使いません。

frontend.learn_grammar.from_rule: Can を伴う仮定法第一形 (未来の可能性と許可)

正しい文を選びましょう。

Choose the correct sentence:

✓ Correct! ✗ Not quite. Correct answer: If he calls, I will maybe tell him the news.
If節は現在形を使い、「will maybe」は主節で正しく可能性を表しています。「May be」は状態を表すときに使います。

frontend.learn_grammar.from_rule: 第一条件文：多分/おそらく (May/Might)

文を完成させるために正しい動詞の形を選びましょう。

If you study hard, you ___ pass the exam.

✓ Correct! ✗ Not quite. Correct answer: can
仮定法第一文型では、条件が現実的または起こりそうな場合、主節で能力を表すために「can」（「will can」ではない）を使います。

frontend.learn_grammar.from_rule: Can を伴う仮定法第一形 (未来の可能性と許可)

文を完成させるために正しい形を選びましょう。

If you study consistently, you ___ definitely improve your English.

✓ Correct! ✗ Not quite. Correct answer: can
If you study consistently, you *can* definitely improve your English. 「can」は能力や強い可能性を表します。「will」も正しいですが、「can」は能力というニュアンスを加えます。

frontend.learn_grammar.from_rule: 第一条件文：助動詞（can, might, should）の使い方

文を完成させるために正しい形を選びましょう。

If she studies hard, she ___ pass the exam.

✓ Correct! ✗ Not quite. Correct answer: may
ここでは「May」が正しく可能性を表しています。「Will probably」も可能ですが、「may」は少し確実性が低いことを示し、それが良い選択肢となります。

frontend.learn_grammar.from_rule: 第一条件文：多分/おそらく (May/Might)

文の間違いを見つけて修正しましょう。

Find and fix the mistake:

If I finish work early, I will might join you.

✓ Correct! ✗ Not quite. Correct answer: If I finish work early, I might join you.
「will」と「might」を一緒に使うことはできません。「might」はすでに未来の可能性を表しているので、「will」は不要です。

frontend.learn_grammar.from_rule: 第一条件文：多分/おそらく (May/Might)

Score: /8

よくある質問 (6)

基本的な構造は「If + 現在形, 主語 + 助動詞 (can/might/should) + 動詞の原形」です。例えば、「If it rains, we might stay inside.」のように使います。
「First Conditional」での「can」は、能力、可能性、または許可を表します。例えば、「If you practice, you can get better.」（能力）のように使います。
一番大切なのは、確実性の「度合い」を表現することなんです。基本的な仮定法1型（willを使う場合）は、結果がほぼ確実だというニュアンスがあります。でも、「maybe」「probably」「may」「might」を使うと、その確実性を少し下げて、結果が起こる可能性はあるけど保証はできない、という感じになるんです。例えば、「もし時間があれば、行くかもしれません。」は
If I have time, I may come.
となりますね。
「will probably」は「たぶん～するでしょう」という感じで、条件が満たされたら、結果が起こる可能性が高いことを示します。かなり自信がある時に使いますね。「may」や「might」はもっと一般的な「～かもしれない」という可能性で、結果が起こるかもしれないけど、そこまで確実ではない時に使います。例えば、「電車に乗り遅れるかもしれない。」は
I might miss the train.
と言えますよ。
ある特定の条件が満たされた場合に、未来の行動が「ability」（能力や機会）として可能であるか、または「permission」（許可）として許されるかを表現することです。例えば、「If it stops raining, we can go out」（もし雨が止んだら、外出できます）のように使います。
条件の結果が能力、許可、または機会に関する場合に「can」を使います。「will」は一般的な予測や確実な未来の結果に使います。比較してみましょう：「If I finish early, I can meet you」（能力）と「If I finish early, I will meet you」（確実性）。
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