L'impératif: Comment dit-on en français?

Traduire en français l'impératif du verbe donné.
Let's work!
!

Do your homework! (pl.)
vos devoirs!

Don't speak English in class! (pl.)
anglais en classe!

Be nice! (pl.)
gentilles!

Be nice! (sing.)
gentille!
Let's go to the movies!
au cinéma!

Study! (sing.)
!

Go to the library! (sing.)
à la bibliothèque!

Let's dance!
!

Don't lose! (sing.)
!
Let's finish!
!

Don't buy this dress! (sing.)
cette robe!

Let's not have a dog.
de chien.

Let's go!
!

Speak louder! (sing.)
plus fort!