Preoxygenation
[医] 预充氧[呼吸]法
🗣️ 情景例句
The main course: steak and potatoes.
主菜 牛排和马铃薯。
Rain before seven; fine before eleven.
雨过天晴。
There were no classes this afternoon. My classmates all went to People's Park.
今天下午没有课。同学们都到人民公园去了。