B1 · 中級 チャプター 5

Expressing Cause, Path, and Rate with 'Por'

6 トータルルール
62 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

Master 'Por' to explain the 'why', 'how', and 'where' of your Portuguese journey.

  • Express the cause or reason behind any action or emotion.
  • Describe movement through spaces and the methods used to communicate.
  • Calculate rates, prices, and time durations accurately.
Connect your thoughts with the power of 'Por'.

学べること

Hey, ready to level up your Portuguese? This chapter is all about 'Por' – that little word with HUGE power! You'll stop just getting by and start explaining things like a pro. Ever wondered how to say *why* something happened, or that you walked *through* a beautiful park? What about how much something costs *per* kilo, or that you studied *for* hours? 'Por' is your answer to all of these! We'll dive into its six main roles: explaining the *cause* or *reason* behind actions, describing *movement through a space* (like

walking along the river
), identifying the *means* or *method* of an action (sent by mail), and even talking about *rates* and *durations* of time (working per day). By understanding how 'por' connects these ideas – cause, path, method, rate, time – you'll unlock a whole new layer of expression. You'll master nuanced differences between 'por' and 'para', helping you avoid common mistakes intermediate learners make. After this, you'll effortlessly chat about *why* you love Portuguese, *how* you learned it, and *for how long* you've been practicing, making your conversations much more natural and engaging. Get ready to sound truly B1!

Learning Objectives

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

  1. 1
    By the end you will be able to explain the reason for an action using 'por causa de' or 'por' + noun.
  2. 2
    By the end you will be able to navigate a city by describing paths 'through' or 'along' specific landmarks.
  3. 3
    By the end you will be able to discuss prices per unit and frequency of habits per time period.

チャプターガイド

Overview

Hey there, language learners! Ready to unlock a super versatile and incredibly common word in Portuguese grammar? This chapter is all about 'Por' – a tiny preposition with immense power that's absolutely crucial for reaching a B1 Portuguese level and beyond.
Mastering 'Por' will significantly boost your ability to express complex ideas, making your conversations much more natural and precise. You'll stop just translating word-for-word and start thinking like a native speaker. We'll explore how 'Por' helps you explain *why* something happened, describe *movement through a space*, identify the *means* or *method* of an action, and even talk about *rates* and *durations* of time.
By the end of this guide, you’ll effortlessly differentiate 'Por' from its sometimes-confusing cousin, 'Para', avoiding common intermediate mistakes and truly sounding like a pro. Get ready to express cause, path, and rate with confidence!

How This Grammar Works

The preposition 'Por' is a workhorse in Portuguese, connecting ideas in numerous ways. Let's break down its key functions, which are essential for any B1 Portuguese speaker.
First, 'Por' is fundamental for Expressing Cause & Reason. It tells us *why* something happens or *because of what*.
* Ele fez isso por amor. (He did that out of love.)
* A reunião foi adiada por causa da chuva. (The meeting was postponed because of the rain.)
Next, it's used for Expressing Cause, Exchange & Path. While cause is covered above, 'Por' also indicates exchange (like trading one thing for another) and movement along or through a path.
* Troquei meu carro por uma moto. (I exchanged my car for a motorcycle.)
* Caminhamos pela floresta. (We walked through the forest.) – Note pela is por + a.
This leads us to Portuguese Prepositions: Through and Along (Por). It describes movement *through* or *along* a place.
* Passamos por Lisboa. (We passed through Lisbon.)
* Andei pelo parque. (I walked through/along the park.) – Again, pelo is por + o.
'Por' is also vital for Means, Methods, and Agents. It specifies *how* an action is performed or *by whom* (in passive sentences).
* Enviei a carta por correio. (I sent the letter by mail.)
* O livro foi escrito por um autor famoso. (The book was written by a famous author.)
When talking about quantities or frequencies, we use 'Por' for Saying 'Per' or 'By': Rates with Por.
* Custa dez euros por quilo. (It costs ten euros per kilo.)
* Trabalho oito horas por dia. (I work eight hours per day.)
Finally, Por for Time (Duration & Approximation) indicates a duration of time or an approximate period.
* Estudei por três horas. (I studied for three hours.)
* Ele virá por volta das cinco. (He will come around five o'clock.)
Mastering these uses of 'Por' will significantly enhance your understanding of Portuguese grammar and your ability to communicate effectively.

Common Mistakes

  1. 1✗ Wrong: Fiz o trabalho para meu amigo. (I did the work for my friend.)
✓ Correct: Fiz o trabalho por meu amigo. (I did the work for my friend – *meaning on behalf of/instead of him*)
*Explanation:* While para often means for (purpose, destination), por is used when you do something *on behalf of* someone, or *in exchange for* them. If you did the work *for* your friend *so they could have it*, you might use para. But if you did it *because your friend couldn't*, por is correct.
  1. 1✗ Wrong: Viajamos para o trem. (We traveled to the train.)
✓ Correct: Viajamos de trem. (We traveled by train.) OR Viajamos por trem. (Less common, but still means by train).
*Explanation:* When referring to the means of transportation, de is most common. However, por can also be used for means/method, especially in more formal contexts or when emphasizing the *channel* through which something occurs. Para indicates destination, not the means of travel itself.
  1. 1✗ Wrong: Estudei para cinco horas. (I studied for five hours.)
✓ Correct: Estudei por cinco horas. (I studied for five hours.)
*Explanation:* To express a duration of time, por is the correct preposition. Para implies a purpose or destination, not how long an action lasted.

Real Conversations

A

A

Por que você está tão feliz hoje? (Why are you so happy today?)
B

B

Estou feliz por ter passado no exame! (I'm happy because I passed the exam!)
A

A

Você prefere viajar de carro ou por trem? (Do you prefer to travel by car or by train?)
B

B

Prefiro ir por avião, é mais rápido. (I prefer to go by plane, it's faster.)
A

A

A encomenda chegou por correio ou por uma transportadora? (Did the package arrive by mail or by a shipping company?)
B

B

Chegou por uma transportadora, foi entregue por um motorista. (It arrived by a shipping company, it was delivered by a driver.)

Quick FAQ

Q

What's the main difference between por and para when expressing purpose?

Para typically expresses purpose or destination (

for the sake of,
to), while por implies cause, reason, or exchange (because of, on behalf of, in exchange for).

Q

Can por always be replaced by pelo/pela?

Pelo (por + o) and pela (por + a) are contractions of por with definite articles. They are used when por is followed by a masculine or feminine singular noun, respectively. So, no, por isn't *always* replaced; it depends on whether an article follows.

Q

How do native speakers use por to talk about approximate time?

They often use phrases like por volta de (around/approximately) or simply por followed by a general time period, like por estes dias (around these days).

Cultural Context

In everyday Portuguese, 'Por' is incredibly common and often used fluidly. Native speakers might sometimes use 'por' in ways that seem subtle to learners, especially in idiomatic expressions. For instance,
obrigado por...
(thank you *for*...) is a fixed expression using por to indicate the reason for gratitude.
While regional accents and common phrases vary, the core grammatical functions of 'por' remain consistent across Brazil and Portugal, making it universally understood and essential for authentic communication.

重要な例文 (6)

1

Obrigado por me ajudar com a mudança.

引っ越しを手伝ってくれてありがとう。

ポルトガル語の前置詞「Por」：原因と理由の表現
2

Ela não foi trabalhar pelo cansaço.

彼女は疲れが原因で仕事に行きませんでした。

ポルトガル語の前置詞「Por」：原因と理由の表現
3

Eu caminhei pelo parque hoje de manhã.

I walked through the park this morning.

ポルトガル語の前置詞：〜を通って・〜に沿って (Por)
4

Ela gosta de correr pela praia ao pôr do sol.

She likes to run along the beach at sunset.

ポルトガル語の前置詞：〜を通って・〜に沿って (Por)
5

Eu vou ao ginásio três vezes **por** semana.

私は週に3回ジムに行きます。

「〜につき」「〜ごとに」と言う：Porを使った率 (por dia, pelo quilo)
6

O limite de velocidade é 120 km **por** hora.

制限速度は時速120キロです。

「〜につき」「〜ごとに」と言う：Porを使った率 (por dia, pelo quilo)

ヒントとコツ (4)

⚠️

「プン」の法則に注意！

por と不定冠詞の um/uma は絶対に合体させないで！ por um を縮めて言うと、ポルトガル語で「おなら」を意味する pum に聞こえてしまいます。
Comprei o presente por um bom preço.
frontend.learn_grammar.from_rule: ポルトガル語の前置詞「Por」：原因と理由の表現
💡

「交換」のルール

お金を払う時や、何かを別のものと交換する（お願いを聞いてもらう時も！）時は、必ず 'Por' を使います。取引の合図だと思ってね。
Troquei meu celular por um novo.
frontend.learn_grammar.from_rule: 前置詞 Por：原因、交換、経路の表現
💡

Contractions are mandatory

Never write 'por o' or 'por a'. Always use 'pelo' or 'pela'.
frontend.learn_grammar.from_rule: ポルトガル語の前置詞：〜を通って・〜に沿って (Por)
💡

WhatsAppのルール

アプリやサイトの話をする時は、ほとんどの場合 pelo を使います。 'aplicativo' や 'site' は男性名詞だからです。：
Vi isso pelo Instagram.
frontend.learn_grammar.from_rule: ポルトガル語の前置詞「Por」：手段、方法、動作主

重要な語彙 (7)

motivo reason troca exchange caminho path/way correio mail quilo kilogram durante during (often synonymous with por in time) através through

Real-World Preview

shopping-cart

At the Local Market

clock

Explaining a Delay

Review Summary

  • Verbo + por + Substantivo
  • Verbo de Movimento + pelo/pela + Local
  • Número + por + Unidade

よくある間違い

Use 'para' for purpose (to do something) and 'por' for cause. Since seeing birds is the goal/purpose, 'para' is required.

Wrong: Vou para o parque por ver os pássaros.
正解: Vou ao parque para ver os pássaros.

In Portuguese, 'por' must contract with definite articles. 'Por' + 'a' always becomes 'pela'.

Wrong: Eu ando por a rua.
正解: Eu ando pela rua.

In passive voice, the agent (the person doing the action) is introduced by 'por', not 'para'.

Wrong: O livro foi escrito para Machado de Assis.
正解: O livro foi escrito por Machado de Assis.

このチャプターのルール (6)

1

ポルトガル語の前置詞「Por」：原因と理由の表現

B1
出来事の「きっかけ」や「理由」という、過去にさかのぼる視点を持つのが por です。pelo や pela の形を使いこなして理由を伝えましょう。
Obrigado por me ajudar com a mudança.
10 例文
2

前置詞 Por：原因、交換、経路の表現

B1
目的地よりも、そこに至るまでの「プロセス」「理由」「通り道」「交換」を伝えたい時は por （または pelo/pela）を使いましょう。
Eu paguei uma fortuna pelo novo iPhone.
10 例文
3

ポルトガル語の前置詞：〜を通って・〜に沿って (Por)

B1
Use 'por' (contracted as 'pelo/pela') for any movement that traverses a space or follows a specific path.
Eu caminhei pelo parque hoje de manhã.
11 例文
4

ポルトガル語の前置詞「Por」：手段、方法、動作主

B1
「どうやって（手段）」と「誰が（動作主）」を説明する魔法の言葉 por を、pelo や pela などの短縮形と一緒にマスターしましょう！
Mandei a foto pelo WhatsApp.
11 例文
5

「〜につき」「〜ごとに」と言う：Porを使った率 (por dia, pelo quilo)

B1
「por」は頻度を表す por dia や、対価を払う pelo jantar など、割合や交換を伝えるための万能ツールです。
Eu vou ao ginásio três vezes **por** semana.
10 例文
6

時間の Por (期間とおおよそ)

B1
時間の「流れ（期間）」や「だいたいの時間帯」は por、締め切りや期限は para と使い分けましょう。
Vou ficar offline por umas duas horas para estudar...
10 例文

Next Steps

You've just unlocked one of the most versatile tools in the Portuguese language. Your ability to explain reasons and paths will make your conversations much more fluid. Keep practicing those contractions!

Narrate your walk to work/school using 'pelo/pela'.

Look at a grocery receipt and state prices 'por quilo'.

Continue to: Nuanced Comparisons and Passive Actions

クイック練習 (10)

Correct the sentence.

Find and fix the mistake:

Fiz isso por o meu pai.

✓ Correct! ✗ Not quite. Correct answer: Fiz isso pelo meu pai.
Por + o = pelo.

frontend.learn_grammar.from_rule: ポルトガル語の前置詞：〜を通って・〜に沿って (Por)

頻度を表すフレーズを完成させましょう。

Eu bebo café duas vezes ___ dia. (I drink coffee twice a day)

✓ Correct! ✗ Not quite. Correct answer: por
頻度（一定期間に何回）を言う時は、常に 'por' を使います。

frontend.learn_grammar.from_rule: 「〜につき」「〜ごとに」と言う：Porを使った率 (por dia, pelo quilo)

原因を表すこの文の間違いを直してください。

Não saímos por a chuva forte.

✓ Correct! ✗ Not quite. Correct answer: Não saímos pela chuva forte.
Chuva は女性単数名詞です。 por + a は必ず pela に縮約させます。

frontend.learn_grammar.from_rule: ポルトガル語の前置詞「Por」：原因と理由の表現

前置詞の使い方に間違いがある箇所を見つけてください。

Obrigado para o presente!

✓ Correct! ✗ Not quite. Correct answer: Obrigado pelo presente!
感謝を表す 'Obrigado' は、対象となるものに対して常に 'por' を使います。 por + o = pelo です。

frontend.learn_grammar.from_rule: 前置詞 Por：原因、交換、経路の表現

「交換」を正しく表している文はどれですか？

正しい文を選んでください：

✓ Correct! ✗ Not quite. Correct answer: Comprei o livro por 20 reais.
価格や交換について話す時は、常に 'por' を使います。

frontend.learn_grammar.from_rule: 前置詞 Por：原因、交換、経路の表現

前置詞の間違いを直しましょう。

O carro vai a 100km para hora.

✓ Correct! ✗ Not quite. Correct answer: O carro vai a 100km por hora.
速度（時速〜）を言う時は para ではなく por を使います。

frontend.learn_grammar.from_rule: 「〜につき」「〜ごとに」と言う：Porを使った率 (por dia, pelo quilo)

Fill in the blank with the correct contraction.

Eu passei ___ parque.

✓ Correct! ✗ Not quite. Correct answer: pelo
Parque is masculine, so por + o = pelo.

frontend.learn_grammar.from_rule: ポルトガル語の前置詞：〜を通って・〜に沿って (Por)

Fill in the blank.

O projeto foi aprovado ___ diretoria.

✓ Correct! ✗ Not quite. Correct answer: pela
Diretoria is feminine.

frontend.learn_grammar.from_rule: ポルトガル語の前置詞：〜を通って・〜に沿って (Por)

正しい縮約形（pelo, pela, pelos, pelas）を空欄に入れてください。

Ela está muito feliz ___ novo emprego.

✓ Correct! ✗ Not quite. Correct answer: pelo
Emprego は男性単数名詞なので、por + o = pelo になります。

frontend.learn_grammar.from_rule: ポルトガル語の前置詞「Por」：原因と理由の表現

正しい合体形（pelo, pela, pelos, pelas）を選んで空欄を埋めてください。

Eu passo ___ centro da cidade todos os dias.

✓ Correct! ✗ Not quite. Correct answer: pelo
Centro は男性単数名詞 (o centro) なので、 'por' + 'o' が合体して 'pelo' になります。

frontend.learn_grammar.from_rule: 前置詞 Por：原因、交換、経路の表現

Score: /10

よくある質問 (6)

ポルトガル語では、前置詞と冠詞が合体してリズムを整えるルールがあるからです。 Pelo atraso. のように、話す時も書く時も必須ですよ。
原因をよりはっきりと強調したい時に使います。「まさに〜のせいで」と言いたい時にぴったりです。
Por causa de ti.
'para' は矢印が的に当たる「目的地・ゴール」、 'por' は矢印が空を飛んでいる「プロセス・原因・経路」だと考えて。
Vou para o Rio por São Paulo.
（サンパウロ経由でリオへ行く）という感じです。
次に来る言葉を見てみて。特定の「その公園」のように 'the' (o/a) がつく名詞なら、合体させて pelo parque (por + o) になります。 por sorte （運良く）のように冠詞がいらない時はそのままです。
Use 'pelo' when 'por' is followed by the masculine article 'o'. It is a mandatory contraction.
It is common, but in informal Brazilian Portuguese, it is often omitted.
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The Rules of Pronoun Placement
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Nuanced Comparisons and Passive Actions
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