Well they are different because in the u.s they call it subway if I'm right (I'm from the uk) also in France it's not underground like in the U.S. for the simalarties, they both use trains and I'm not sure of another. Hope this helped!
Hi !
je dois m'étirer avant de faire de l'exercice.
The rule is =
When a verb follows another one which is conjugated in a simple tense it has to be infinitive tense........
M'étirer
m'étire = je m'étire
tu t'étires
il/elle/on s'étire
nous nous étirons
vous vous étirez
ils/elles s'étirent
:)