—_________ your friend play the guitar? —Yes, he _________.
A: Do; do
B:Is; is
C:Can; can't
D:Can/ can
设命题甲:关于x的不等式x2+2ax+4>0对一切x∈R恒成立,命题乙:对数函数y=log4-2ax在0,+∞上递减,那么甲是乙的( )