A:地表崎岖,喀斯特地貌显著
B:千沟万壑,水土流失严重
C:地形平坦,一望无际
D:雪山连绵,冰川广布
Where did Mary go last Saturday?
①△AEF∽△CAB;②CF=2AF;③DF=DC;④tan∠CAD= 2 .
其中正确的结论有( )