English verb conjugation
COULD BACKFILL

Regular verb: backfill - backfilled - backfilled

Affirmation

Simple form	V-ing form
I could backfill you could backfill she could backfill we could backfill you could backfill they could backfill	I could be backfilling you could be backfilling she could be backfilling we could be backfilling you could be backfilling they could be backfilling
Perfect	V-ing perfect
I could have backfilled you could have backfilled she could have backfilled we could have backfilled you could have backfilled they could have backfilled	I could have been backfilling you could have been backfilling she could have been backfilling we could have been backfilling you could have been backfilling they could have been backfilling

Negation

Simple form	V-ing form
I couldn't backfill you couldn't backfill she couldn't backfill we couldn't backfill you couldn't backfill they couldn't backfill	I couldn't be backfilling you couldn't be backfilling she couldn't be backfilling we couldn't be backfilling you couldn't be backfilling they couldn't be backfilling
Perfect	V-ing perfect
I couldn't have backfilled you couldn't have backfilled she couldn't have backfilled we couldn't have backfilled you couldn't have backfilled they couldn't have backfilled	I couldn't have been backfilling you couldn't have been backfilling she couldn't have been backfilling we couldn't have been backfilling you couldn't have been backfilling they couldn't have been backfilling

Interrogative form

Simple form	V-ing form
could I backfill? could you backfill? could she backfill? could we backfill? could you backfill? could they backfill?	could I be backfilling? could you be backfilling? could she be backfilling? could we be backfilling? could you be backfilling? could they be backfilling?
Perfect	V-ing perfect
could I have backfilled? could you have backfilled? could she have backfilled? could we have backfilled? could you have backfilled? could they have backfilled?	could I have been backfilling? could you have been backfilling? could she have been backfilling? could we have been backfilling? could you have been backfilling? could they have been backfilling?

Interro-negative form

Simple form	V-ing form
couldn't I backfill? couldn't you backfill? couldn't she backfill? couldn't we backfill? couldn't you backfill? couldn't they backfill?	couldn't I be backfilling? couldn't you be backfilling? couldn't she be backfilling? couldn't we be backfilling? couldn't you be backfilling? couldn't they be backfilling?
Perfect	V-ing perfect
couldn't I have backfilled? couldn't you have backfilled? couldn't she have backfilled? couldn't we have backfilled? couldn't you have backfilled? couldn't they have backfilled?	couldn't I have been backfilling? couldn't you have been backfilling? couldn't she have been backfilling? couldn't we have been backfilling? couldn't you have been backfilling? couldn't they have been backfilling?