A:C,H,N,P,Mn
B:Cl,Fe,S,N,Mg
C:Cu,Zn,Mn,Mo
D:N,P,K,Cu,Fe,I
如图,已知矩形ABCD中,AB=2,在BC上取一点E,沿AE将△ABE向上折叠,使B点落在AD上的F点处,若四边形EFDC与矩形ABCD相似,则AD=( )