The scene is the master frame so it has no parent (the NULL pointer).

此场景是主画面对象，没有祖先。

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This article classifies frame-support structure into master frame and master support.

文章首先将框架一支撑结构分开为总框架和总支撑。

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The master frame is characteristic of shear structure deformation and the master support features bending cantilever bar deformation.

总框架具有剪切结构的变形特征，总支撑则具有弯曲悬臂杆的变形特征。

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The tubes are carefully whittled and cut by a master craftsperson to produce certain notes when the bamboo frame is shaken or tapped.

UNESCO: Culture