A:直线
B:线段
C:射线
如图所示,小明将悬挂的轻质小球紧靠音叉,用小锤轻敲和重敲音叉时,小球弹开的角度不同.比较角度的大小是为了探究( )
Broadway has been well-known for its theatres since the early ____ century. (twenty)