English verb conjugation
COULD STALE

Regular verb: stale - staled - staled

Affirmation

Simple form	V-ing form
I could stale you could stale he could stale we could stale you could stale they could stale	I could be staling you could be staling he could be staling we could be staling you could be staling they could be staling
Perfect	V-ing perfect
I could have staled you could have staled he could have staled we could have staled you could have staled they could have staled	I could have been staling you could have been staling he could have been staling we could have been staling you could have been staling they could have been staling

Negation

Simple form	V-ing form
I couldn't stale you couldn't stale he couldn't stale we couldn't stale you couldn't stale they couldn't stale	I couldn't be staling you couldn't be staling he couldn't be staling we couldn't be staling you couldn't be staling they couldn't be staling
Perfect	V-ing perfect
I couldn't have staled you couldn't have staled he couldn't have staled we couldn't have staled you couldn't have staled they couldn't have staled	I couldn't have been staling you couldn't have been staling he couldn't have been staling we couldn't have been staling you couldn't have been staling they couldn't have been staling

Interrogative form

Simple form	V-ing form
could I stale? could you stale? could he stale? could we stale? could you stale? could they stale?	could I be staling? could you be staling? could he be staling? could we be staling? could you be staling? could they be staling?
Perfect	V-ing perfect
could I have staled? could you have staled? could he have staled? could we have staled? could you have staled? could they have staled?	could I have been staling? could you have been staling? could he have been staling? could we have been staling? could you have been staling? could they have been staling?

Interro-negative form

Simple form	V-ing form
couldn't I stale? couldn't you stale? couldn't he stale? couldn't we stale? couldn't you stale? couldn't they stale?	couldn't I be staling? couldn't you be staling? couldn't he be staling? couldn't we be staling? couldn't you be staling? couldn't they be staling?
Perfect	V-ing perfect
couldn't I have staled? couldn't you have staled? couldn't he have staled? couldn't we have staled? couldn't you have staled? couldn't they have staled?	couldn't I have been staling? couldn't you have been staling? couldn't he have been staling? couldn't we have been staling? couldn't you have been staling? couldn't they have been staling?