A:why were you late
B:why are you late
C:why you were late
D:why you are late
读亚洲气候分布图,判断哪种说法正确:
非洲热带草原地区对人们生产﹑生活影响最大的自然灾害是( )
在密闭容器中进行反应:X(g)+3Y(g)⇌2Z(g),有关下列图象的说法正确的是( )