铁证

tiě zhèng rú shān

铁证如山

mountain of ironclad evidence

bèi wàng lù shì tā cān jiā de tiě zhèng

备忘录是他参加的铁证。

His memo is ironclad proof he was involved.

wǒ yǒu tā wú zuì de tiě zhèng

我有她无罪的铁证。

I had incontestable proof of her innocence.