Let AD=x, then BD = 50× 20-x =1000-x. 。

∫∠EAC = 60，

∴∠CAB=90 -60 =30。

In Rt△BCD,

∫∠FBC = 45，

∴∠CBD=∠BCD=45，

∴CD=DB= 1000-x.

In Rt△ACD,

∫∠CAB = 30，

∴CD=tan30？ AD，

That is db = CD = tan 30? AD= 1000-x=33x，

Solution: x≈633.98,

∴CD= 1000-633.98=366.02.

A: The distance from Building C to AB Expressway is 366.02 meters.