IMPERATIVE MOOD.
qu'il y ait, let there be.

SUBJUNCTIVE MOOD.

Present.
qu'il y ait, that there may be.
Imperfect.
qu'il y eût, that there might be.
Past.
qu'il y ait eu, that there may have been.
Pluperfect.
qu'il y eût eu, that there might have been.

INFINITIVE MOOD.

Present.
y avoir, to be there.
Past.
y avoir eu, to have been there.

Participle.

Present.
y ayant, there being.
Compound.
y ayant eu, there having been.

N. B.--In the same manner: il n'y a pas; il y en a; il n'y en a pas.

Interrogative.