?椭圆螺栓孔

... 螺栓 bolt; screw bolt; threaded b ... 椭圆螺栓孔 elliptic bolt hole 半圆头螺栓 ahead bolt; ball headed bolt; ball stud; button headed bolt; button-headed bolt; cup head bolt; cup-headed bolt; half-round screw; snap head bolt; snap-head bolt ...