Object Mode(オブジェクトモード)とEdit Mode(編集モード)
When adding curves there are some common options like other Objects.
In Object/Edit Mode, the Add Surface menu, provides six different surface primitives:
Adds a generic curve of four control points forming an arc.
Adds an a closed loop of control point forming a circle. Note, a circle NURBS surface is never filled, unlike its "real" curve counterpart...
Adds a generic surface patch consisting of a 4×4 grid plane with the center grid slightly raised.
Adds an open end cylinder, consisting of an extruded NURBS Circle.
Adds a generic sphere constructed by revolving a grid of control points about an axis.
Adds a doughnut-shaped primitive created by rotating a circle around an axis.