Petscheckite
铌钽铁铀矿
🗣️ 情景例句
And have you had an engineer come in to do an inspection?
你们可有一个工程师来做过检查吗？
All things are difficult before they are easy.
凡事都是先难后易。
Opportunity knocks but once.
机不可失，时不再来。