Here's why it's not a real term:
* Tense refers to the time of an action or state. Common tenses in English include past, present, and future.
* "Dubious" means uncertain or questionable.
Therefore, "dubious tense" doesn't make grammatical sense.
Perhaps you're thinking of something else related to:
* Uncertain verb conjugation: If someone uses a verb form incorrectly, you might say their grammar is "dubious" or "questionable."
* Imprecise time reference: A sentence might be ambiguous about the time of an action, leading to uncertainty about the intended tense.
* Figurative language: Someone might use "dubious tense" humorously to describe a situation where the timing or sequence of events seems uncertain or confusing.
If you have a specific example of a sentence or situation that you're referring to, please provide it, and I can help you understand the grammatical issue.