CN tower is one of _________ towers in the world.
运动会的发令枪,所用的“火药”是用氯酸钾和红磷混合制成的,一经撞击两种物质就剧烈反应,发出响声并产生白烟.白烟的成分是( )
已知a<b,则下列不等式一定成立的是( )
My dad is going to Cuba _____________. He will stay there for a week.