C:2 CH3OH+O2 = 2CO2+4H2O△H=-22.68 kJ·mol-1
A:CH3OH(l)+3/2O2(g) = CO2(g) +2H2O(l) △H=-725.8 kJ·mol-1
B:2 CH3OH(l)+3O2(g) = 2CO2(g)+4H2O(l) △H='+1451.6' kJ·mol-1
D:CH3OH(l)+3/2O2(g) = CO2(g)+2H2O(g)△H=-725.8 kJ·mol-1
设α为常数,求证:y=f(x)=cos2x+cos2(x+α)﹣2cosαcosxcos(x+α).表示平行于x轴的直线(α≠kπ,k∈Z).
我国的审判机关是( )
①水土流失现象不断加剧
②沙尘暴急剧增加,风沙危害严重
③生态环境受到严重威胁
④引发世界性人口的流动,该地人口急剧增加.
It's time ____ have ____.