从...就知道了
Reach for this when one small piece of evidence is enough to draw a bigger conclusion — 'you can tell just from X.' It's the Chinese version of 'the name alone tells you everything' or 'just look at the price and you know.' Useful in arguments, gossip, and explanations where you want to point at a single tell and have the listener fill in the rest.
Structure
从 [CLUE] 就知道了
cóng... jiù zhīdào le
How to Think About It
The 从 plants a single piece of evidence; 就 says 'this alone is enough'; 知道了 lands the conclusion as already obvious. The whole pattern compresses 'I looked at this one thing, and that was enough to know everything I needed.' Native speakers feel this as a slightly knowing, sometimes sarcastic shortcut — you're skipping the full argument because the clue is so telling.
Examples
从他的口音就知道了, 他是北方人。
Cóng tā de kǒuyīn jiù zhīdào le, tā shì běifāng rén.
Just from his accent you can tell — he's a northerner.
从价格就知道了, 这家店不便宜。
Cóng jiàgé jiù zhīdào le, zhè jiā diàn bù piányi.
Just from the price you can tell — this place isn't cheap.
从书名就知道了, 这是一本爱情小说。
Cóng shūmíng jiù zhīdào le, zhè shì yì běn àiqíng xiǎoshuō.
Just from the title you can tell — this is a romance novel.
Common Mistake
Learners drop the 就, but without it the pattern loses the 'this alone is enough' punch. '从名字知道了' sounds like a half-finished thought; 就 is what makes the clue feel sufficient.
从他的脸色, 我知道他生气了。
从他的脸色就知道他生气了。
Don't Confuse With
看...就知道
Very similar — 'just look at X and you know.' Use 看 when there's a visual cue you're literally looking at; use 从 when the evidence is more abstract (a name, a number, a fact).
由此可见
Formal written equivalent — 'from this it can be seen.' Use in essays and arguments; 从...就知道了 is for speech and casual writing.
一看就知道
'One look and you know.' Snappier and more colloquial, focused on instant visual recognition. 从...就知道了 has space for a non-visual clue.
Practice
___ 名字就知道了。
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从
从他的眼神 ___ 知道了。
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就
Put in order: [就知道了 / 价格 / 从]
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从价格就知道了。
Translate to Chinese: 'Just from her smile you can tell she's happy.'
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从她的笑容就知道了, 她很开心。
Write one sentence using 从...就知道了 to draw a conclusion from a small clue.
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Example answer: 从他穿的衣服就知道了, 他很有钱。 (Just from his clothes you can tell — he's rich.)
Hear It in Real Episodes
This pattern appears in 1 Fluentide episode: