idiom > Tongxintiedan
Contents
铜心铁胆
Pinyin: tóng xīn tiě dǎn

Explanation: 形容人的意志坚定。

No. 2
　　Someone who's strong-willed. Minja Chung-name "Xiao Shulan" Second off: "Since ancient times, the eyes greedy for every scholar, unlike copper which health Intuit Heart Tie Dan."
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