因为...所以 (because...so)
Expressing cause and effect with 因为...所以
I can express cause and effect using 因为...所以
Look at these examples. Can you spot the grammar pattern?
因为今天很冷，所以我穿了外套。
Because it's cold today, I wore a jacket.
因为我很忙，所以没去。
Because I was busy, I didn't go.
他很累，所以想睡觉。
He's tired, so he wants to sleep.
Pay attention to the highlighted parts. What do they have in common?
因为...所以
Chinese expresses cause and effect with a paired conjunction: 因为 (yīnwèi, because) + 所以 (suǒyǐ, so/therefore).
Structure: 因为 + cause，所以 + result
| Chinese | Pinyin | English |
|---|---|---|
| 因为下雨，所以我不去。 | Yīnwèi xià yǔ, suǒyǐ wǒ bú qù. | Because it's raining, I'm not going. |
| 因为太贵，所以没买。 | Yīnwèi tài guì, suǒyǐ méi mǎi. | Because it was too expensive, I didn't buy it. |
Key rule: You can use BOTH together, or just one: 因为下雨，我不去 or 下雨，所以我不去. But in English you cannot say *'Because it rained, so I stayed' — Chinese CAN and often does use both.
Common Error Patterns
Avoided using both 因为 and 所以 together (English interference)
Chinese allows and encourages using BOTH 因为 and 所以 in one sentence. Don't avoid the paired pattern.
因为今天很冷，所以我穿了外套。
Because it's cold today, I wore a jacket.
因为 (cause: cold) + 所以 (result: wore jacket). Both connectors used together — perfectly natural in Chinese.
因为我很忙，所以没去。
Because I was busy, I didn't go.
Note 没去 (méi qù) — negation of completed action uses 没, not 不. The 因为...所以 frame is separate from the negation rule.
他很累，所以想睡觉。
He's tired, so he wants to sleep.
Using only 所以 (without 因为) is fine — the cause is implied from context. Both halves are optional independently.
Practice in course
Apply this grammar in A1 course exercises