Learn Farsi: کمدین بیم دارد که حضار نخندند. - The comedian fears that the audience will not laugh.

Verbs expressing fear or apprehension, such as بیم داشتن (to fear), require the verb in the following که clause to be in the subjunctive mood. Even though we translate it as a future action ('will not laugh'), Farsi uses the subjunctive to show the uncertainty of the feared event.

Where is the usual بـ prefix for the subjunctive in نخندند?

When making a subjunctive verb negative, the negative prefix نـ completely replaces the subjunctive prefix بـ. You never use both together. So, the positive subjunctive بخندند becomes the negative subjunctive نخندند.

The English translation uses the singular word 'audience', but the verb نخندند has the plural ending ـند. Why?

The word حضار is an Arabic broken plural meaning 'those present' or 'attendees'. Because it refers to a plural group of people in Farsi, it requires the plural verb ending ـند, even though the English collective noun 'audience' typically takes a singular verb.

Is there a difference between using بیم دارد and می‌ترسد in this sentence?

They are very similar, but بیم داشتن is slightly more formal and often implies a sense of apprehension about a future outcome. ترسیدن is the more everyday verb for 'to fear', and it would also work perfectly well here.