1. so and only used in inverted sentences

Inversion in the adverbial clause of result

In the adverbial clause introduced by “so…that” or “such…that”, the main clause should be used in partly inverted order if the “so” or “such” phrase is put before the main clause.

Example:

So intent was the Cossack on his stalking that he was upon the thing Rainsford had made before he saw it.   (Para. 27)

2. but for and if…were… used in unreal conditional clauses