What is a S-IV sentence pattern?

There is no recognized grammatical pattern called "S-IV" in traditional sentence analysis. It's likely you are referring to a different pattern, perhaps a variation or a term used within a specific context.

To help me understand what you mean, could you please provide more information? For example:

* Where did you encounter this term? (e.g., a textbook, a lecture, an online resource)

* What is the context? (e.g., what kind of writing or speech is being analyzed?)

* What do you think the S-IV pattern might be? (e.g., do you have an example sentence?)

With more context, I can accurately identify what you're looking for and explain the appropriate sentence pattern.