选出下列划线字解释全都正确的一项 ( )
I want to buy some postcards in the shop, ______ I don't have enough money.
已知半径R的球的球面上有三个点,其中任意两点间的球面距离都等于πR3,且经过这三个点的小圆周长为4π,则R=( )