如图是“某半球经纬网图”,根据图中信息,判断A点的经纬度为( )
A:30°S,30°W
B:30°N,30°E
C:30°N,30°W
D:30°S,30°E
如图所示的电路中,电压表V1的示数为9伏,电压表V2的示数为3伏,那么R1与R2的阻值之比为( )
— How much did the new watch your sister? — She 350 yuan for it.
肺泡外缠绕着丰富的毛细血管,这有利于( )