——David, could you tell me _________?——Every four years.
A:when the 2014 World Cup will finish
B:how often the World Cup takes place
C:how many teams take part in the World Cup
D:who may score the most goals in the World Cup
由5个完全相同的正方体组成的立体图形如图所示,则它的俯视图是( )
挂在树上的苹果,静止时受到的一对平衡力是( )
下列器官不属于人体消化系统的是( )
我国领土的最南端位于( )