I should have done this. VS I should have been to do this

Question

1. I should have done this.

2. I should have been done this.

3. I should have been to do this.

I have not too much idea about english but I want to know that, grammatically above sentences are correct or not? Please someone let me know.

Answer 1

The first sentence, 'I should have done this', is a grammatically correct sentence, meaning that I regret not having done something. Neither of the other two sentences would be spoken by a native English speaker.

Answer 2

Your first example, I should have done this is grammatically correct, good English.

Your second two examples *I should have been done this and *I should have been to do this, would not generally be produced, and would not generally be recognized as grammatical, by a native English speaker.

In ordinary English, should have... (similarly would have or could have) is a past modal verb used together with a perfect infinitive that expresses the action that one should have (would have, could have) done. "Should" is the past tense of "shall" (similarly, "would" is the past tense of "will" and "could" of "can").

When you use it together with a present-tense verb (e.g. "You should go to the store") it typically expresses an expectation or an obligation (i.e., what you ought to do now or in the future).

However, when you use it together with a perfect infinitive, a past perfect phrase like "... have done," "... have gone," "... have taken," "... have eaten," "... have spoken," etc. it typically expresses a counterfactual possibility, a lost opportunity or a regret over something that did not happen. (When I was looking around for some references on this question I noticed that several language-learning sites call this and similar phrases "modals of lost opportunity".)

The way you should think about this grammatically is:

• [SUBJECT] [should] [have DONE...] [PREDICATE]

That is, the main verb in the sentence is "should" and its auxiliary verb is a past perfect verb, such as "have gone," "have written," "have lifted," "have done," etc. For example:

• I should have done this.
• I should have gone to the store.
• I should have called my mother yesterday.
• I should have eaten the cake.
• I should have given her the necklace.

And so on. This would be the normal pattern for expressing past, lost opportunities.

There are some cases where you might say "... should have been done." But that is because have been done is a passive voice phrase, that is, a phrase in which the subject of the sentence is not the person or thing doing the action (the agent), but rather the person or thing that the action is done to (the patient). So for example, a native English speaker would say:

• This should have been done yesterday. ("this" is the thing being done, not the thing doing it)
• I should have been told. (I am not the one telling something; someone else might have told me, but they didn't)
• The car should have been repaired. (the car is the thing to be repaired, not the one doing the repairing)
• The message should have been sent before noon.

And so on.