Pourquoi le phénomène d'élision se rencontre, p. ex., dans « j'espère » et pas dans « tu espères » ? Quelle est la différence ?
Quand l'élision est-elle nécessaire ?
Why is the phenomenon of elision encountered for instance in "j'espère" and not in "tu espères"? What is the difference ?
When is elision necessary?
Elision is not used formally for "tu"; it's simply a matter of usage; in the spoken language it is acceptable and rendered by "t'espères" in print; however it can be considered as quite lax by many.
Elision is necessary for "je" when the verb that follows starts by a vowel; when the verb starts with "h", usage varies.
Je happe, j'honore, je hasarde, (très rare) j'hasarde
In fact, the difference is a matter of whether "h" is one or the other of the so-called "h-muet" and "h-aspiré". See for instance the link below;
https://www.francaisfacile.com/exercices/exercice-francais-2/exercice-francais-61194.php
