Naaqs
[医][=National Ambient Air Quality Standards]国家环境空气质量标准
🗣️ 情景例句
Then it's settled.
就这样定了。
There's a cool breeze this evening.
今晚有凉爽的微风。
What do you find hardest in English?
你觉得学习英语哪方面最难？