should要提前，你可以百度一下。☺️☺️

Yeah, “should” has many meanings. One meaning is a kind of formal “if”. You’ll usually see it in formal situations like “Should you fail to pass your exam, you will not be allowed to attend university” You’re less likely to see it in casual situations. “Should it rain later, I’ll stay inside”. Although this would be correct too.

The short answer is yes. "Should" is functioning much like "if" often does in the condition clause. But unlike "if" which may or may not trigger the Subjunctive mood, "should" always expresses even more uncertainty and automatically triggers the Subjunctive.

这里是if的虚拟吧