Regarding conditional sentences in standard usage, analyze the statements.

I. Zero conditional typically uses present simple in both clauses to state general truths.
II. In first conditional, will belongs in the main clause when indicating a real possibility.
III. Second conditional uses past simple in the if-clause and would plus base form to discuss remote situations.
IV. Third conditional uses past perfect in the if-clause and would have plus past participle to imagine a past alternative.
V. Mixed conditionals are restricted to present conditions with future consequences in formal registers.

Which statements are CORRECT?