Sintercorundum
烧结金刚砂
🗣️ 情景例句
What are you up to?
你在忙些什么？
The two parties involved in a contract have the obligation to execute the contract.
合同双方有义务履行合同。
He collected tetters and made copies of people's diaries.
他收集到一些信件，复印了一些人的日记。