expert in every phase of corporate activity是形容词短语作定语用来修饰These executives,
became是谓语动词,再此作谓语,
in the industrial machine是介词短语作状语
此句较难理解的地方是These executives, expert in every phase of corporate activity,其实去掉逗号就容易理解了These executives expert in every phase of corporate activity became the indispensable cogs in the industrial machine.
之所以在expert in every phase of corporate activity前后各加一个逗号,其目的在于强调