A:0°
B:20°N
C:23.5°N
D:30°S
已知镁可以在某种气体中燃烧,用化学方程式表达为:2Mg+X2MgO+C,则X的化学式为____ ;该反应属于四种基本反应类型中的____ 反应.标出氧化镁中镁元素的化合价____ .
选择单词,补全短文
hot China winter people old east
Shanghai is the biggest city in ____.It's in the ____ of China. It's got a lot of ____.It's an ____ city. It's very ____ in summer and it's cold in ____.