This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.

Passage: The verbal system lacks a distinctive future tense (the present tense serves here) and features special forms to express an action performed by an undetermined subject (the "impersonal"). Question: What does Estonian use to show actions performed by an undecided subject?
special forms