N2(g)+3H2(g)⇌2NH3(g),△H<0,在673K,30MPa下,n(NH3)和n(H2)随时间变化的关系如图所示,叙述正确的是( )
按照我国交通管理的规定,“红灯停、绿灯行、黄灯预备”,规定红灯发出的光作为交通的停止信号,其原因是____。
读下图,图中山脉,属于我国南北方分界线的是( )
It's 11: 00 pm now, but the light in Peter's room is still on. He must have forgotten _______ before going to bed.