In phrases with “kept” (and perhaps there are other participles that have the same effect?), such as:
He kept it secret.
It was kept hidden.
Do these (nominal) adjectives function effectively as adverbs? Could they be called proper adverbs in these instances?
They are all clearly adjectives, yet in these examples, they all answer the questions:
How did he keep it? (He kept it secret.)
How was it kept? (It was kept hidden.)
That is, these adjectives all function as adverbs because they describe the action of the verb “to keep”, i.e. they can answer a “how” question (in this case) or could be stated as “kept in a X way”—is this a correct assertion?
