以 ... 为由
Reach for 以...为由 when someone gives a stated reason — often one you suspect is just a convenient pretext — for an action. 'On the grounds of X' or 'using X as a reason.' Almost exclusively written and formal, common in news reports about lawsuits, government actions, dismissals, refusals. Slightly skeptical in tone: it flags the reason rather than endorsing it.
Structure
[SUBJECT] 以 [STATED REASON] 为由 [VERB / ACTION]
yǐ... wéi yóu...
How to Think About It
以...为由 frames the reason as official-record speech, not necessarily as truth. A neutral 因为 would say WHY something happened; 以...为由 says 'here's the reason they OFFERED.' That's why it shows up so much in news — reporters can name the stated justification without endorsing it. The slot inside is almost always a short noun phrase: '国家安全', '健康原因', '环保', '违规'. Long sentences inside don't fit.
Examples
公司以业绩下滑为由解雇了他。
Gōngsī yǐ yèjì xiàhuá wéi yóu jiěgù le tā.
The company fired him on the grounds of declining performance.
政府以国家安全为由禁止了这款应用。
Zhèngfǔ yǐ guójiā ānquán wéi yóu jìnzhǐ le zhè kuǎn yìngyòng.
The government banned this app on national security grounds.
他以家中有事为由提前离开了会议。
Tā yǐ jiā zhōng yǒu shì wéi yóu tíqián líkāi le huìyì.
He left the meeting early, citing a family matter.
Common Mistake
Learners use 以...为由 in casual speech or for everyday personal reasons. It's a formal news/legal phrase; in conversation, use 因为 or '说是因为...'. Also, the slot inside must be a noun or noun phrase — not a full clause.
我以我累了为由不去。
他以身体不适为由请了假。
Don't Confuse With
因为 ...
Neutral cause-and-effect, no skepticism. Use 因为 in speech and when the reason is plainly true. 以...为由 hints the reason is a stated pretext.
借口 ...
Even more openly skeptical: 借口 outright calls the reason a flimsy excuse. 以...为由 stays neutral on the surface but cool in tone.
以 ... 为名
'In the name of X.' Similar formal structure but emphasizes invoking a label or banner ('in the name of justice'). 以...为由 specifically marks a reason offered for an action.
Practice
他 ___ 健康原因为由辞职了。
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以
学校以天气恶劣 ___ 取消了运动会。
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为由
Put in order: [以 / 隐私 / 为由 / 他 / 拒绝 / 回答]
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他以隐私为由拒绝回答。
Translate to Chinese: 'They suspended the contract on the grounds of safety concerns.'
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他们以安全问题为由暂停了合同。
Write one news-style sentence about an institution citing a reason for an action, using 以...为由.
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Example answer: 法院以证据不足为由驳回了起诉。 (The court dismissed the lawsuit on the grounds of insufficient evidence.)
Hear It in Real Episodes
Related Grammar Patterns
Acquire by listening
Hear 以 ... 为由 in real Chinese, not in a textbook.
Fluentide picks the next news episode at your level, so this pattern shows up again and again in real context. The transcript marks it, the audio drills it. Free to start, no card.