A:what; no matter whom
B:that; whoever
C:which; whomever
D:that; no matter who
如图△ABC中,DE∥BC,ADAB=23,M为BC上一点,AM交DE于N.
(1)若AE=4,求EC的长;
(2)若M为BC的中点,S△ABC=36,求S△ADN.
乌拉尔山以东依次排列的地形区是( )