Learn French: Tu dois être ferme quand tu parles. - You must be firm when you speak.

Tu dois être ferme quand tu parles.

You must be firm when you speak.

Breakdown of Tu dois être ferme quand tu parles.

être

to be

you (informal singular)

Questions & Answers about Tu dois être ferme quand tu parles.

Since this lesson is about giving commands (the imperative), why didn't we use an imperative here?

Using Tu dois (You must) followed by an infinitive like être is a very common way to give a strong instruction without using the actual imperative tense. If we wanted to use a true imperative direct command here, we would drop the subject pronoun and say Sois ferme quand tu parles (Be firm when you speak).

Why is être in its infinitive (unconjugated) form?

In French, when you have two verbs back-to-back, the second verb is almost always left in the infinitive (the dictionary form). Because the first verb dois is already conjugated to match Tu, the following verb être stays unconjugated.

If I am speaking to a woman, do I need to add an extra -e to ferme?

No, it stays exactly the same. When a French adjective already ends in an -e in its masculine form (like ferme), you do not add another -e to make it feminine.

Do I pronounce the -s at the end of tu parles?

No, the -s is completely silent. For regular -er verbs in the present tense, the tu form is written with an -s, but you do not pronounce it. You say it exactly as you would pronounce je parle or il parle.