如图，∠AOB=90°，∠AOC=36°，∠COD:∠COB=1:2，则∠BOD的度数为(    )

∵∠AOB=90°，∠AOC=36°
∴∠COB=∠AOB-∠AOC
       =90°-36°
       =54°
∵∠COD:∠COB=1:2
∴OD平分∠BOC
∴∠BOD=∠COB=×54°=27°
故选C．

略