如图所示,连接OB,OC.∵△ABC、△BCD都是边长为1的等边三角形,∴OB⊥AD,OC⊥AD,OB=OC= AC×CD AD = 1×1 12+12 = 2 2 .∴OB2+OC2=BC2,∴∠BOC=90°.∴三棱锥A-BCD的体积V= 1 3 S△BOC×AD= 1 3 × 1 2 ×( 2 2 )2× 2 = 2 12 .故选D.