∵∠APC=∠ABP+∠BAP=60+∠BAP=∠APD+∠CPD=60+∠CPD，∴∠BAP=∠CPD．又∵∠ABP=∠PCD=60°，∴△ABP∽△PCD．∴ AB CP = BP CD ，即 3 2 = 1 CD ．∴CD= 2 3 ．故选B．
