在△ABC中,D为BC中点,AB=5,AC=3,AB,AD,AC成等比数列,则△ABC的面积为( )。
下列不属于鸟类繁殖的是( )
A.孔雀开屏
B.大雁南飞
C.雌鸟喂雏
D.母鸡孵蛋
We _____ more than 1,200 English words already, do you know?
A.learn
B.will learn
C.have learned
D.are learning