I don't understand how these sentences were converted from an adjective to an adverb can someone explain.

Adjective sentence: It is obvious that the account should be written off.

Adverb sentence: The account should be written off.

  • I'm not a native English speaker. But this is how I interpreted, the first example is telling that's a write-off account because of the previous sentence "It's obvious that" ("write-off" used as an adjective to mention the account type; and write-off means - "A write-off is a reduction of the recognized value of something"). And in the second example, "off" (adverb) modifies the verb "written". I'm not sure about it. Let's wait for some better answer. – Raj 33 Jan 3 '18 at 15:16
  • 'It is obvious that' is a comment clause, in this case a pragmatic marker giving the speaker's / writer's opinion of how obvious the facts of the matter are. – Edwin Ashworth Jan 3 '18 at 21:00

The only adjective in your first sentence is 'obvious'.

In both sentences, 'written off' is a (phrasal) passive participle. 'Off' could be considered an adverb, but it is usually taken as part of a phrasal verb, since 'write off' has an idiomatic meaning beyond 'write' and 'off'.

In "a write-off", 'write-off' is a noun, and in "a written off account", 'written off' is a (passive) participle phrase used as an adjective.