English verb conjugation
COULD DISCOVER

Regular verb: discover - discovered - discovered

Affirmation

Simple form	V-ing form
I could discover you could discover he could discover we could discover you could discover they could discover	I could be discovering you could be discovering he could be discovering we could be discovering you could be discovering they could be discovering
Perfect	V-ing perfect
I could have discovered you could have discovered he could have discovered we could have discovered you could have discovered they could have discovered	I could have been discovering you could have been discovering he could have been discovering we could have been discovering you could have been discovering they could have been discovering

Negation

Simple form	V-ing form
I couldn't discover you couldn't discover he couldn't discover we couldn't discover you couldn't discover they couldn't discover	I couldn't be discovering you couldn't be discovering he couldn't be discovering we couldn't be discovering you couldn't be discovering they couldn't be discovering
Perfect	V-ing perfect
I couldn't have discovered you couldn't have discovered he couldn't have discovered we couldn't have discovered you couldn't have discovered they couldn't have discovered	I couldn't have been discovering you couldn't have been discovering he couldn't have been discovering we couldn't have been discovering you couldn't have been discovering they couldn't have been discovering

Interrogative form

Simple form	V-ing form
could I discover? could you discover? could he discover? could we discover? could you discover? could they discover?	could I be discovering? could you be discovering? could he be discovering? could we be discovering? could you be discovering? could they be discovering?
Perfect	V-ing perfect
could I have discovered? could you have discovered? could he have discovered? could we have discovered? could you have discovered? could they have discovered?	could I have been discovering? could you have been discovering? could he have been discovering? could we have been discovering? could you have been discovering? could they have been discovering?

Interro-negative form

Simple form	V-ing form
couldn't I discover? couldn't you discover? couldn't he discover? couldn't we discover? couldn't you discover? couldn't they discover?	couldn't I be discovering? couldn't you be discovering? couldn't he be discovering? couldn't we be discovering? couldn't you be discovering? couldn't they be discovering?
Perfect	V-ing perfect
couldn't I have discovered? couldn't you have discovered? couldn't he have discovered? couldn't we have discovered? couldn't you have discovered? couldn't they have discovered?	couldn't I have been discovering? couldn't you have been discovering? couldn't he have been discovering? couldn't we have been discovering? couldn't you have been discovering? couldn't they have been discovering?