Identify the singular subject pronoun in the sentences given below:
I should have learn computer.

The correct answer is: I

The correct answer is "I".
Here, the speaker is thinking that he should have learned computer and the verb is "have learned". Since the pronoun "I" completes the actin of learning computer, it is considered the subject of the sentence. Thus, it serves as the subject pronoun, and the correct answer is "I".