条件从句 meaning in English

protasis

Conditionals and modals
条件从句和情态动词
Mixed conditionals . conditional sentences combine present and past time to talk about hypothetical situations
各种条件相混合；现在时态和过去时态相混合的虚拟条件从句。
Positing what protasis would the contraction for such several schemes become a natural and necessary apodosis
假定一个什么样的条件从句，这几种计划的缩约辞，就会成为自然而必然的结论句？