Learn Farsi: نقشه را با خودت ببر مبادا در جنگل گم شویم. - Take the map with you lest we get lost in the forest.

The conjunction مبادا (lest / so that not) expresses a hypothetical or preventative outcome, which always triggers the present subjunctive for the verb that follows it. Here, گم شویم is the present subjunctive of گم شدن (to get lost) for the 'we' form.

The translation means 'so that we don't get lost'. Why isn't the Farsi verb negative (like گم نشویم)?

The word مبادا already carries a negative meaning ('so that not'). When you use it, the verb that follows remains in the affirmative subjunctive. Adding a negative prefix to the verb would create an unintended double negative.

Why do we use ببر (from بردن) for 'take' instead of بگیر (from گرفتن)?

In Farsi, بردن means 'to take' in the sense of transporting or carrying something away with you. گرفتن means 'to take' in the sense of grabbing or receiving. Since you are carrying the map into the forest, ببر (the imperative of بردن) is the correct choice.

Why does the sentence use خودت (yourself) instead of just the pronoun for 'you' in با خودت?

When an object or prepositional pronoun refers back to the subject of the sentence, Farsi uses a reflexive pronoun (خود + personal ending). Since the subject is an implied 'you' giving a command, you must use خودت (yourself) to say 'with you'.