The advantage of using sub models is that they can exist independently of the main model.

使用子模型的优势在于它可以独立地存在主模型。

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Sub-menu appears when some section in the main menu is selected.

当选择了主要菜单中的一些部分时就会出现下级菜单。

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Processes (main process, sub process, services, tasks)

流程（主要的流程、子流程、服务、任务）

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Adversarial relationships between customers, main contractors and sub-contractors mean that design changes often cause rows and that problems are not tackled until they reach crisis proportions.

ECONOMIST: Are British builders uniquely awful?

Work to expand the refinery was sub-contracted by Total's main contractor - engineering firm Jacobs - to an Italian company, IREM, which decided to use its own foreign workforce.

BBC: Foreign labour row 'deal reached'

Until now, Montblanc's chronographs have featured traditional hour and minute hands on the main dial and smaller rotating disk sub-dials with stationary hands to measure elapsed minutes and seconds.

WSJ: The Face of Watchmaking's Future at SIHH and GTE