The usage of 'IS OF' (Knowledge is of two kinds...)

[Infin1ty]

Hello everyone,

I'd like to ask you a question about the usage of 'is of' in the sentence below. I could understand what they mean, but I don't know how and when to use 'is/be of'. Could you please explain it to me? Many thanks.

Knowledge is of two kinds...

Phenom X4 family may be of interest only to those users...

Is it possible for me to say:

This is a private conversation and is of (that is) none of your business.
_________________
Please feel free to correct me if you find any mistakes in my posts.

[Alan]

Hi Infnity,

'Of' is probably the most common preposition and has many functions. In your examples it ,as it were, introduces a phrase referring back to the preceding noun. In other words 'of two kinds' refers back to 'knowledge' and 'Phenom X4 family' is described as having interest for the users.

In you last sentence you would have to say: This is a private conversation and is none of your business

Alan
_________________
English as a Second Language
You can read my ESL story Present Simple

[Mister Micawber]

.
This is not idiomatic. It is just the verb 'be' and the preposition 'of':

Knowledge is power.
Knowledge is valuable.
Knowledge is of two kinds.

'Of interest' is a fixed phrase and means 'interesting':

Phenom X4 family may be of interest.
Phenom X4 family may be interesting.

Your 3rd sentence construction is not possible.
.
_________________
Native English teacher at Mister Micawber's

[Infin1ty]

Thank you for your detailed explanations, Alan and Mister Micawber.
_________________
Please feel free to correct me if you find any mistakes in my posts.