在△ABC中,AB=5,AC=3,BC=7,则∠BAC=( )
A:π6
B:π3
C:2π3
D:5π6
估计7-2的值在( )
— What wonderful music!
— Thanks. Neither my classmates nor my mother ______ the piano better than me.
下列说法不正确的一项是 ( )