Plural nouns acquire plural verbs.
A novel noun takes a singular action-word.
These two sentences are quite obvious examples.
But what happens whether it be a compound noun rather than a simple noun?
Bad Example: "Permeability and porosity has been measured in the science lab."
Here you have a couple of things, permeability and porosity, staying tested, so while all of these nouns is single, jointly they take a plural verb.
Corrected Case: "Permeability and also porosity?are being scored within the laboratory."
(Indeed, we spell. the term "laboratory" unless it can be component of?the proper name of an company.)
Consider the phrase "and" to be a wedding ring. When it adheres two nouns into a compound subject, the 2 main registered users?become a pair and wish for to take a dual action-word - as long as they each shall live.
Ah, the way romantic!