之所以...是因为...: Explaining Why in Chinese
之所以…是因为/是由于…
之所以...是因为/是由于... states an outcome or established situation first, then identifies the reason that explains it. The construction places explanatory focus on the latter cause and often links back to prior discourse. This card covers the paired frame; independent nominal or topic uses of 之所以 and continuations such as 就在于 also exist.
Published July 20, 2026
Reviewed July 20, 2026
01 / PATTERN
See the Structure
MODEL
之所以 + Outcome, 是因为/是由于 + Reason
Read the structure
之所以...是因为/是由于... states an outcome or established situation first, then identifies the reason that explains it. The construction places explanatory focus on the latter cause and often links back to prior discourse. This card covers the paired frame; independent nominal or topic uses of 之所以 and continuations such as 就在于 also exist. Keep the model 之所以 + Outcome, 是因为/是由于 + Reason visible while you compare each sentence.
这次活动之所以成功，是因为大家准备得很充分。
The reason this event succeeded is that everyone prepared thoroughly.
Choose the right context
To name a known outcome before explaining its cause: 这次活动之所以成功，是因为大家准备得很充分。 To connect back to a situation already mentioned and then supply its explanation. To focus the reader's attention on the reason, using 是因为 or the often more formal 是由于.
我们之所以推迟出发，是因为天气突然变坏了。
The reason we delayed our departure is that the weather suddenly worsened.
Respect the boundary
When you want the ordinary cause-first order; 因为...所以... presents the reason before the result. Do not insert 因为 inside the outcome clause or reverse 是因为 into an order that breaks the reason clause. Do not treat every unpaired use of 之所以 as wrong. It can form nominal or topic expressions, and 就在于 is another established continuation.
这次活动之所以因为成功，是因为大家准备得很充分。
(The reason this event succeeded is that everyone prepared thoroughly.)
Repair the pattern
因为 is incorrectly stacked inside the 之所以 outcome clause: The 之所以 clause states the outcome 成功. The causal marker belongs before the later reason clause, not inside the outcome. 是因为 is broken apart and 因为 is placed inside its clause: The reason clause is introduced by 是因为 as a unit here. Put 内容很真实 after that marker.
这次活动之所以成功，是因为大家准备得很充分。
Use the repaired structure without changing the intended meaning.
02 / MAP
Read the Sentence
Read from left to right and notice the job performed by each part. The labels describe this example; they are not a rule that every Chinese sentence must copy.
这次活动之所以成功，是因为大家准备得很充分。
The reason this event succeeded is that everyone prepared thoroughly.
这次
之所以
This part occupies the 之所以 position in the model pattern.
活动
Outcome, 是因为/是由于
This part occupies the Outcome, 是因为/是由于 position in the model pattern.
之所以
Reason
This part occupies the Reason position in the model pattern.
成功
之所以
This part occupies the 之所以 position in the model pattern.
，
Outcome, 是因为/是由于
This part occupies the Outcome, 是因为/是由于 position in the model pattern.
是
Reason
This part occupies the Reason position in the model pattern.
因为
之所以
This part occupies the 之所以 position in the model pattern.
大家
Outcome, 是因为/是由于
This part occupies the Outcome, 是因为/是由于 position in the model pattern.
准备
Reason
This part occupies the Reason position in the model pattern.
得很
之所以
This part occupies the 之所以 position in the model pattern.
充分
Outcome, 是因为/是由于
This part occupies the Outcome, 是因为/是由于 position in the model pattern.
03 / EXAMPLES
Examples You Can Reuse
Keep the structure stable while changing the people, objects, times, or conditions. Pinyin is shown as reading support; use the Chinese sentence and translation to confirm the grammar relationship.
这次活动之所以成功，是因为大家准备得很充分。
The reason this event succeeded is that everyone prepared thoroughly.
我们之所以推迟出发，是因为天气突然变坏了。
The reason we delayed our departure is that the weather suddenly worsened.
这部电影之所以受欢迎，是因为故事很真实。
The reason this film is popular is that its story feels very real.
他之所以进步这么快，是由于每天坚持练习。
The reason he improved so quickly is his consistent daily practice.
之所以选择这个方案，是因为它更符合实际情况。
The reason for choosing this plan is that it better fits the actual situation.
04 / LIMITS
When to Use It — and When Not To
Use it when
- To name a known outcome before explaining its cause: 这次活动之所以成功，是因为大家准备得很充分。
- To connect back to a situation already mentioned and then supply its explanation.
- To focus the reader's attention on the reason, using 是因为 or the often more formal 是由于.
Do not use it when
- When you want the ordinary cause-first order; 因为...所以... presents the reason before the result.
- Do not insert 因为 inside the outcome clause or reverse 是因为 into an order that breaks the reason clause.
- Do not treat every unpaired use of 之所以 as wrong. It can form nominal or topic expressions, and 就在于 is another established continuation.
05 / REPAIR
Compare Right and Wrong
Compare the smallest meaningful change. Each explanation identifies a placement, scope, form, or clause relationship instead of treating the whole sentence as one undifferentiated mistake.
这次活动之所以因为成功，是因为大家准备得很充分。
这次活动之所以成功，是因为大家准备得很充分。
因为 is incorrectly stacked inside the 之所以 outcome clause
The 之所以 clause states the outcome 成功. The causal marker belongs before the later reason clause, not inside the outcome.
这部电影之所以受欢迎，是内容因为很真实。
这部电影之所以受欢迎，是因为内容很真实。
是因为 is broken apart and 因为 is placed inside its clause
The reason clause is introduced by 是因为 as a unit here. Put 内容很真实 after that marker.
这次活动之所以因为成功，是因为大家准备得很充分。
The outcome follows 之所以 directly: 之所以成功，是因为大家准备得很充分。
这部电影之所以受欢迎，是内容因为很真实。
Keep 是因为 together before the reason clause: 是因为内容很真实。
06 / PRACTICE
Practice the Grammar Point
Complete three short tasks in order: judge the pattern, repair a common error, and build the sentence. Feedback is fixed and reviewed, so these activities do not use a checker allowance.
1. Judge the sentence
2. Choose the correction
3. Build the sentence
Build a complete sentence with 之所以…是因为/是由于….
07 / APPLY
Apply It in Your Sentence
Write one original sentence with 之所以…是因为/是由于…. Your draft moves to the checker through this browser session, selects this grammar point as the first review focus, and waits for you to submit.
08 / QUESTIONS
之所以...是因为...: Explaining Why Questions
How is 之所以...是因为... different from 因为...所以...?
因为...所以... normally gives the cause first and then the result. 之所以...是因为... puts the outcome or known situation first and makes the following reason the explanatory focus.
Can 是由于 replace 是因为?
Yes. Both can introduce the explanation in this frame. 是由于 often sounds more formal or analytical, but the choice also depends on the surrounding sentence and register.
Must every use of 之所以 be followed by 是因为?
No. This card teaches a common paired construction, but 之所以 also has nominal and topic uses, and forms such as 之所以...就在于... are established. Those alternatives are not automatically errors.
09 / SOURCES
Sources and Review Notes
These references support different parts of the lesson. GF0025-2021 supports level placement only; professional grammar works support the explanation, limits, examples, and cross-checks. Their inclusion does not imply endorsement.
Modern Mandarin Chinese Grammar: A Practical Guide, 3rd ed.
Ross, Ma, Chen, He and Yeh · Routledge · 2024
Locator: Construction index and function chapters relevant to 之所以…是因为/是由于…
Supports the learner-facing account of where 之所以…是因为/是由于… appears and what communicative job it performs.
Official sourceChinese: A Comprehensive Grammar, 2nd ed.
Yip and Rimmington · Routledge · 2016
Locator: Relevant sentence and clause chapters for 之所以…是因为/是由于…
Cross-checks the 之所以 + Outcome, 是因为/是由于 + Reason pattern, clause relationship, and limits represented by the reviewed examples.
Official sourceChinese Proficiency Grading Standards for International Chinese Language Education (GF0025-2021)
Ministry of Education and State Language Commission · Ministry of Education of the PRC · 2021
Locator: Appendix A, combined Levels 7–9 grammar inventory
Supports directory placement at HSK 8 as an internal subdivision of the official advanced band; it does not independently prove usage rules.
Official source10 / CONTINUE
Continue with a Connected Rule
Easy to confuse
因为…所以因为...所以 (Because... So)
Compare result-first causal focus with ordinary cause-first order.
Continue learning
难怪难怪 (nánguài): No Wonder
Use an explicit cause to explain why an outcome is unsurprising.
Continue learning
由此可见由此可见 (yóucǐ kějiàn)
Move from explaining a result to drawing a supported conclusion.
Compare
怪不得怪不得 for Realizing the Cause
Explicit causal focus contrasts with 怪不得 marking the speaker's newly resolved surprise.
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Use an explicit cause to explain why an outcome is unsurprising.