Prepositions of Cause & Purpose: 由于, 因为, 为了
Prepositions of cause and purpose introduce why something happened or what it is for. At HSK 3 these are 因为 (because), 由于 (because of, more formal) and 为了 (in order to, for the sake of).
由于 (yóuyú) "due to, owing to" — more formal/written than 因为. Often opens a sentence, and pairs naturally with a bare noun-phrase reason: 由于...原因/由于经济原因. The result clause doesn't need 所以.
为了 (wèile) "in order to, for the purpose of" — introduces a forward-looking GOAL, not a past reason. Structure: 为了 + goal, + subject + action. ✅ 为了学好汉语，他每天练习。
Key contrast: 因为/由于 answer "why did X happen" (a reason already true); 为了 answers "what is X for" (a goal aimed at). ❌ 为了他生病了 → ✅ 因为他生病了.
Worked examples
| Chinese | Pinyin | English | What it shows |
|---|---|---|---|
| 由于天气不好，比赛取消了。 | Yóuyú tiānqì bù hǎo, bǐsài qǔxiāo le. | Due to bad weather, the match was cancelled. | 由于 introduces a formal reason; no 所以 is needed in the result clause. |
| 为了学好汉语，他每天都练习写汉字。 | Wèile xuéhǎo Hànyǔ, tā měitiān dōu liànxí xiě Hànzì. | In order to learn Chinese well, he practices writing characters every day. | 为了 + goal comes first, then subject + action — a forward-looking purpose, not a past reason. |
| 由于工作太忙，他不得不取消了旅行计划。 | Yóuyú gōngzuò tài máng, tā bùdébù qǔxiāole lǚxíng jìhuà. | Because work was too busy, he had no choice but to cancel his travel plans. | 由于's formal reason clause can lead into a more complex consequence with 不得不. |
Word by word
Each word in this pattern on its own: what it does here, the structure, three more examples, and the mistake to avoid.
由于 (yóu yú)
Gives the reason, a bit more formal than 因为.
Structure: 由于 + reason, (所以) + result
| Chinese | Pinyin | English |
|---|---|---|
| 由于下大雪，飞机晚点了三个小时。 | Yóu yú xià dà xuě, fēi jī wǎn diǎn le sān gè xiǎo shí. | Because of heavy snow, the plane was three hours late. |
| 由于身体不好，他没有参加比赛。 | Yóu yú shēn tǐ bù hǎo, tā méi yǒu cān jiā bǐ sài. | Because of poor health, he did not take part in the contest. |
| 由于堵车，我们迟到了二十分钟。 | Yóu yú dǔ chē, wǒ men chí dào le èr shí fēn zhōng. | Because of the traffic jam, we were twenty minutes late. |
Not: 由于下雨了，因为比赛取消了。 Use only one reason word; the result clause can take 所以.
In the official HSK 3.0 grammar outline: level 4, conjunctions (连接分句或句子); level 4, prepositions (引出原因).
由于 is also explained in: Formal vs. informal register differences (HSK 4) · 由于/因为 (formal): due to (HSK 4) · Preposition 随着 (along with, as) (HSK 5).
因为 (yīn wèi)
Gives the reason for something that has already happened or is true.
Structure: 因为 + reason, (所以) + result
| Chinese | Pinyin | English |
|---|---|---|
| 因为路上堵车，所以我来晚了。 | Yīn wèi lù shàng dǔ chē, suǒ yǐ wǒ lái wǎn le. | Because of the traffic, I came late. |
| 我没吃早饭，因为我起晚了。 | Wǒ méi chī zǎo fàn, yīn wèi wǒ qǐ wǎn le. | I did not eat breakfast because I got up late. |
| 他因为生病，没来上课。 | Tā yīn wèi shēng bìng, méi lái shàng kè. | He did not come to class because he was ill. |
Not: 我因为学好汉语，每天听录音。 因为 gives a past reason; for a goal use 为了.
In the official HSK 3.0 grammar outline: level 2, conjunctions (连接分句或者句子); level 2, prepositions (引出原因).
因为 is also explained in: Causal Sentences: 因为…所以 (HSK 2) · 由于/因为 (formal): due to (HSK 4).
为了 (wèi le)
Gives the goal or purpose of an action.
Structure: 为了 + goal, + action
| Chinese | Pinyin | English |
|---|---|---|
| 为了给妈妈买礼物，他打了一个月的工。 | Wèi le gěi mā mā mǎi lǐ wù, tā dǎ le yí gè yuè de gōng. | To buy a present for his mother, he worked part time for a month. |
| 为了身体健康，我每天走路上班。 | Wèi le shēn tǐ jiàn kāng, wǒ měi tiān zǒu lù shàng bān. | For the sake of my health, I walk to work every day. |
| 为了不迟到，我今天五点就起床了。 | Wèi le bù chí dào, wǒ jīn tiān wǔ diǎn jiù qǐ chuáng le. | So as not to be late, I got up at five today. |
Not: 他为了身体不好，去看医生。 为了 names a goal; being unwell is a reason, so use 因为.
In the official HSK 3.0 grammar outline: level 3, prepositions (引出目的、原因).
为了 is also explained in: Conditional & Purpose Clauses: 要是…就, 为了… (HSK 3).
Compared side by side: 因为 vs 为了.
What you need first
Every topic in GraphChinese names its own prerequisites, and these are the grammar points this one is built on. If a sentence here will not parse, one of them is why.
What this opens up
These patterns list Prepositions of Cause & Purpose among their own prerequisites, so they become readable once this one holds.
Questions about Prepositions of Cause & Purpose
What does 原因目的介词 (Prepositions of Cause & Purpose) mean in Chinese?
Prepositions of cause and purpose introduce why something happened or what it is for. At HSK 3 these are 因为 (because), 由于 (because of, more formal) and 为了 (in order to, for the sake of). It is an HSK 3 grammar point.
How do you use 原因目的介词 (Prepositions of Cause & Purpose) in a sentence?
由于天气不好，比赛取消了。 — Yóuyú tiānqì bù hǎo, bǐsài qǔxiāo le. — Due to bad weather, the match was cancelled. 由于 introduces a formal reason; no 所以 is needed in the result clause.
What do you need to know before 原因目的介词 (Prepositions of Cause & Purpose)?
Causal Sentences (HSK 2). This pattern is built out of them, so a sentence here that will not parse usually means one of them has not landed yet.
What does 原因目的介词 (Prepositions of Cause & Purpose) lead to?
Conditional & Purpose Clauses (HSK 3), 由于/因为 (formal) (HSK 4). Each of them names 原因目的介词 (Prepositions of Cause & Purpose) among its own prerequisites.
What is the difference between 因为 and 为了?
因为 looks back at the cause, and 为了 looks forward at the goal. 因为下雨，我没去 gives the cause. 为了学汉语，我去了北京 gives the aim.
Does 由于 need 所以?
No. 由于 is formal and can stand alone. If you add a link to the result, use 所以 or 因此, but never 因为.
Prepositions of Cause & Purpose is one topic of 829. GraphChinese teaches them in prerequisite order, so this pattern reaches you on the day everything it rests on is proven. The whole course, HSK 0 through HSK 6, is $49 once for lifetime access.
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