既... 也...
Reach for this when you want to attribute TWO simultaneous qualities, reasons, or actions to one subject — 'he's both smart and hardworking,' 'this involves both economics and politics.' 既...也... pairs two parallel ideas as equally true at the same time. More formal than 又...又..., common in essays, analytical writing, and thoughtful speech where you want the parallelism to feel balanced and intentional.
Structure
Subject + 既 [A] 也 [B]
jì... yě...
How to Think About It
既 announces 'here comes the first of two parallel claims about the same subject'; 也 marks the second. Both halves must share the same subject and structure: 既 + adj + 也 + adj, or 既 + verb phrase + 也 + verb phrase. They're peers, not in tension. If the two halves are escalating or contrasting, switch to 不仅...而且... or 虽然...但.... If you mean two simultaneous events with different subjects, use 同时 instead.
Examples
他既聪明也努力。
Tā jì cōngmíng yě nǔlì.
He's both smart and hardworking.
这个决定既考虑了利益，也考虑了风险。
Zhège juédìng jì kǎolǜ le lìyì, yě kǎolǜ le fēngxiǎn.
This decision took both the benefits and the risks into account.
学外语既需要时间，也需要耐心。
Xué wàiyǔ jì xūyào shíjiān, yě xūyào nàixīn.
Learning a foreign language requires both time and patience.
Common Mistake
Learners try to pair 既 with two different subjects, but 既...也... only works when one subject has two parallel qualities or roles. Different subjects need 一边...一边... or 同时.
既哥哥工作，也我工作。
我既要工作，也要照顾孩子。
Don't Confuse With
又...又...
Same 'both A and B' meaning, more colloquial. 又...又... is what you say in chat; 既...也... is what you write in an essay.
不仅...也...
Implies the second item goes beyond the first ('not just X, but also Y'). 既...也... presents A and B as equal peers.
既然...就...
Same 既 character, very different pattern. 既然...就... is 'since X, then Y' (cause→result). 既...也... is parallel attributes. Don't mix them up.
Practice
Fill in: 她____会说英语，也会说中文。
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既
Fill in: 这件事既有好的一面，____有不好的一面。
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也
Arrange: 也 / 既 / 他 / 努力 / 聪明
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他既聪明也努力。
Translate to Chinese: This product is both cheap and good quality.
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这个产品既便宜，也质量好。
Use 既...也... to describe two qualities a person you know has.
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我妈妈既严格，也很温柔。
Hear It in Real Episodes
Related Grammar Patterns
Acquire by listening
Hear 既... 也... 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.