A:少数民族大量内迁
B:豪强地主势力恶性膨胀
C:统治集体内部争权夺利
D:士族势力削弱中央集权
如图,⊙O是正五边形ABCDE的外接圆,则∠CAD=____度.
— What's this?
— It's umbrella.