Can a phrase starting with "if" always be replaced with a phrase with a phrase starting with SHOULD? It doesn't seem like we can make a direct substitution. For example, we say

If he askED you to move to Italy, would you do it?


Should he ask you to move to Italy, would you do it?

Why is this, and what is the rule for the substitution?

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    It's not informal; it's just different. They are different ways to express the same idea. Another way would be to say, "Were he to ask you to move to Italy, would you do it?" These ways don't nuance different meanings; they mean exactly the same thing. Any answer as to "why" would be opinion-based. Which is used is personal preference, and maybe somewhat geographically influenced, but none of them are weird in any locale. Commented Jan 15, 2016 at 16:56
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    Related question, If/should… INVERSION FORM.
    – user140086
    Commented Jan 15, 2016 at 17:20
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    @Jonatan: You are quite right - I didn't read the question properly, because I was making a cup of tea at the time. I initially assumed you were asking about should/would you do it. But I just got back in time to edit the comment and add the bit about asked. I am frankly astonished that someone with your apparent level of competence in English could ask such a question, and I genuinely would be interested to know why the "correct" form isn't obvious to you. But that's an ELL issue, not really relevant to ELU, imho. Commented Jan 15, 2016 at 17:33
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    I think the way your question is phrased is making it easy to misinterpret. You're actually wondering how it is that "should" can be interchanged with "if" given that it can't be used as an exact replacement... Commented Jan 15, 2016 at 17:40
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    @ChrisSunami: Precisely. But I think it's also worth pointing out that in my example above, preceding text clearly shows that ask is a "reduced" form of shall ask (at the time, a credible "subjunctive" alternative to should ask). Commented Jan 15, 2016 at 17:44

2 Answers 2


The first option is correct, the second not. The verb form, should ask is subjunctive and expresses a hypothetical situation that has not yet happened.

The verb form should asked is not a standard form. If you were describing a hypothetical referring to a time already passed, you could say

Should he have asked you ...


If he had asked you ...

But note that these describe something that did not happen.

  • So, the answer is "should he ask you to move to Italy, would you do it?", right? I thought the same. Commented Jan 15, 2016 at 17:19
  • The original question seems to have been edited in a way that makes this answer incorrect / irrelevant. Commented Oct 5, 2018 at 17:19

Modal verbs require verb complements in the infinitive form:

Should he ask ...
He should ask ...

Should SUBJ asked is ungrammatical.

Asked could occur, however, if the complement of the modal is auxiliary BE or HAVE taking asked as its complement:

Should he be asked, he will respond ...
Should he have asked, he would have been told ...

The last one, however, is clumsy; with an irrealis we'd usually say

Had he asked, he would have been told ...

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