tombez

In a sentence

• Ne tombez pas dans ce piège.

  Do not fall into this trap.

  Here, 'tombez' is imperative form used to give instructions or warnings.

• Vous tombez souvent quand vous courez.

  You often fall when you run.

  In this sentence, 'tombez' is in the present tense indicating general action or habit.

• Il faudra surveiller la falaise pour ne pas tomber.

  We need to watch the cliff to avoid falling.

  Although 'tomber' here is in infinitive form, it relates conceptually to 'tombez' through the action it denotes—motion downwards or accidents.