Nitrocementation
碳氮共渗
🗣️ 情景例句
What subject did you major in university?
你在大学主修的科目是什么？
Can I cancel this ticket?
我可以取消这张票吗？
Speculations about is nature have been going on for literally thousands of years,
人们对睡眠作用的种种猜测，确实有数千年之久。