设平面区域,则D绕y轴旋转所成旋转体体积为_____

Becareful,_______you'llfalldown.

则下列结论正确的是（）

________withthesizeofthewholeearth,thehighestmountainsdonotseemhighatall.

Thisdiploma(毕业文凭)________thatyouhavecompletedhighschool.