English verb conjugation
COULD SOLVE

Regular verb: solve - solved - solved

Affirmation

Simple form	V-ing form
I could solve you could solve he could solve we could solve you could solve they could solve	I could be solving you could be solving he could be solving we could be solving you could be solving they could be solving
Perfect	V-ing perfect
I could have solved you could have solved he could have solved we could have solved you could have solved they could have solved	I could have been solving you could have been solving he could have been solving we could have been solving you could have been solving they could have been solving

Negation

Simple form	V-ing form
I couldn't solve you couldn't solve he couldn't solve we couldn't solve you couldn't solve they couldn't solve	I couldn't be solving you couldn't be solving he couldn't be solving we couldn't be solving you couldn't be solving they couldn't be solving
Perfect	V-ing perfect
I couldn't have solved you couldn't have solved he couldn't have solved we couldn't have solved you couldn't have solved they couldn't have solved	I couldn't have been solving you couldn't have been solving he couldn't have been solving we couldn't have been solving you couldn't have been solving they couldn't have been solving

Interrogative form

Simple form	V-ing form
could I solve? could you solve? could he solve? could we solve? could you solve? could they solve?	could I be solving? could you be solving? could he be solving? could we be solving? could you be solving? could they be solving?
Perfect	V-ing perfect
could I have solved? could you have solved? could he have solved? could we have solved? could you have solved? could they have solved?	could I have been solving? could you have been solving? could he have been solving? could we have been solving? could you have been solving? could they have been solving?

Interro-negative form

Simple form	V-ing form
couldn't I solve? couldn't you solve? couldn't he solve? couldn't we solve? couldn't you solve? couldn't they solve?	couldn't I be solving? couldn't you be solving? couldn't he be solving? couldn't we be solving? couldn't you be solving? couldn't they be solving?
Perfect	V-ing perfect
couldn't I have solved? couldn't you have solved? couldn't he have solved? couldn't we have solved? couldn't you have solved? couldn't they have solved?	couldn't I have been solving? couldn't you have been solving? couldn't he have been solving? couldn't we have been solving? couldn't you have been solving? couldn't they have been solving?