. . . -----|||-设曲面Z为锥面 =sqrt ({x)^2+(y)^2} 被平面 z=1 所截得-|||-(iint )_(dfrac {1)(2)}^x(int )_(x)^dxdy=-|||-分的下侧,则 ()()-|||-bigcirc A. -dfrac (sqrt {2)}(3)-|||-bigcirc B. -1-|||-bigcirc C. -2-|||-bigcirc D.0