In the following question, out of the four alternatives, select the alternative which will improve the bracketed part of the sentence. In case no improvement is needed, select "no improvement". I should (has to be) with them tonight.

Introduction / Context:
This sentence improvement question tests knowledge of English verb forms with modal verbs. The given sentence is I should (has to be) with them tonight. The bracketed phrase is ungrammatical, and we must choose the best replacement from the options. Correct handling of modals like should, must, and might with perfect aspects such as have been is a common grammar area in competitive exams. Here the sense is of an obligation or expectation in the past regarding being with them tonight.

Given Data / Assumptions:

• The original sentence uses the modal should followed by a bracketed verb phrase has to be that we need to correct.
• The subject is I and the time reference is tonight, which may be understood as present or near future from the speaker point of view.
• The intended meaning is likely to express regret or obligation that was not fulfilled, which is commonly expressed using should have been.
• Options include has been, have been, been, no improvement, and had been.
• We assume the exam expects standard, modern British or Indian English usage.

Concept / Approach:
The phrase should have been is the correct form when we want to express that it would have been proper or desirable for something to happen, often implying that it did not happen. Should must be followed by the base form of the verb, and when we want the perfect aspect, we use have plus the past participle. Therefore, I should have been with them tonight is the standard structure. Has been and had been cannot directly follow should because modals always take the bare infinitive form, not third person singular or past perfect forms.

Step-by-Step Solution:
Step 1: Recognise that should is a modal verb and must be followed by a base verb, not has, had, or is forms. Step 2: To express an expectation or obligation related to an event that did not occur, English uses should have plus the past participle. Step 3: The past participle of be is been, so the correct structure is should have been. Step 4: Compare this with the options. Option B is have been, which when combined with should gives I should have been. Step 5: Option A, has been, would make I should has been, which is wrong because has is never used after should. Step 6: Option C, been, would give I should been, which is incomplete and grammatically incorrect. Step 7: Option D, no improvement, would keep has to be, which does not follow should in normal usage in this meaning. Step 8: Option E, had been, would give I should had been, which is also incorrect, since had is a finite verb and cannot follow should. Step 9: Therefore, replacing the bracketed part with have been produces the correct sentence I should have been with them tonight.

Verification / Alternative check:
Consider similar examples. We say I should have gone, not I should has gone or I should had gone. Likewise, we say You should have been more careful. The structure is should plus have plus past participle. The sentence I should have been with them tonight clearly expresses a sense of regret about not being there. This consistent pattern confirms that have been is the right choice for the bracketed part.

Why Other Options Are Wrong:
Has been is wrong because should has been is never used in standard grammar; has is used for present perfect with a subject like he or she, not as a complement to should. Been alone does not include the auxiliary have and therefore cannot form the perfect aspect. No improvement would leave a non standard phrase has to be, which would need a different structure such as I have to be with them tonight to be correct. Had been is a past perfect form that would require a different subject and auxiliary pattern, and cannot directly follow should in this sentence.

Common Pitfalls:
Learners often confuse have to, which expresses obligation, with should have, which expresses expectation or regret. In this question, the presence of should shows that we are in the realm of modal usage and that the perfect form must be built with have been. Another pitfall is to choose no improvement when the original phrase sounds somewhat familiar but is actually incorrect. Always test the sentence mentally against other examples you know before choosing no improvement.

Final Answer:
The correct improvement is have been, so the sentence becomes I should have been with them tonight.