The rudimentary parts of a sentence are the noun and verb.
You must understand rudimentary math before you tackle quadratic equations. (rudimentary = basic)
Though she had read several books on quantum physics, she still had only a rudimentary grasp on the subject.
When describing something simple and basic for example... Ralph and Simon built a rudimentary shelter from branches and palm fronds.
most Chinese managers-especially those at senior levels in major companies-have at least rudimentary fluency in English, the business language of the world."