Hello! My name’s John. I’m in Beijing now. It’s hot in Beijing. It’s sunny too.
I can wear my shorts and shirt. My shorts are green. I have a new jacket. My old jacket is too small. I want to buy a hat.The hat is very pretty, but it is $60. that’s very expensive.
The hat is cheap.
光明学校文学社决定举办“我爱祖国文学”为主题的读书报告会，现请你参与完成以下几项工作：
2NH3的正、逆反应速率可用各反应物或生成物浓度的变化来表示，下列各关系中能说明反应已达到平衡状态的是 （ ）