如图, 山坡AC与水平面AB成30°的角,沿山坡AC每往上爬100米,则竖直高度上升( )米
A:503
B:502
C:50
D:30
苏联成立和解体的时间分别是( )
—May I speak to the headmaster? —He a meeting now. Can I take a message?