This is the longest street in the city. We lived here for a long time.
Esta es la calle más larga de la ciudad. Vivimos aquí por mucho tiempo.
I have not seen them for a long time.
No los he visto desde hace mucho tiempo.
Note.—When a phrase expressing duration of time introduced by for is equivalent to since ... ago, for is translated desde hace.
(a) The phrase to be long (in), followed by a verbal in -ing, expressed or understood, is rendered tardar (en), followed by an infinitive expressed or understood.
Have patience! You will not be long in learning how to do it.
¡Ten paciencia! No tardarás en aprender a hacerlo.
You go now. I will follow.—All right, but don't be long.
Vete ahora. Yo te seguiré.—Bueno, pero no tardes.