English verb conjugation
COULD IMPROVE

Regular verb: improve - improved - improved

Affirmation

Simple form	V-ing form
I could improve you could improve he could improve we could improve you could improve they could improve	I could be improving you could be improving he could be improving we could be improving you could be improving they could be improving
Perfect	V-ing perfect
I could have improved you could have improved he could have improved we could have improved you could have improved they could have improved	I could have been improving you could have been improving he could have been improving we could have been improving you could have been improving they could have been improving

Negation

Simple form	V-ing form
I couldn't improve you couldn't improve he couldn't improve we couldn't improve you couldn't improve they couldn't improve	I couldn't be improving you couldn't be improving he couldn't be improving we couldn't be improving you couldn't be improving they couldn't be improving
Perfect	V-ing perfect
I couldn't have improved you couldn't have improved he couldn't have improved we couldn't have improved you couldn't have improved they couldn't have improved	I couldn't have been improving you couldn't have been improving he couldn't have been improving we couldn't have been improving you couldn't have been improving they couldn't have been improving

Interrogative form

Simple form	V-ing form
could I improve? could you improve? could he improve? could we improve? could you improve? could they improve?	could I be improving? could you be improving? could he be improving? could we be improving? could you be improving? could they be improving?
Perfect	V-ing perfect
could I have improved? could you have improved? could he have improved? could we have improved? could you have improved? could they have improved?	could I have been improving? could you have been improving? could he have been improving? could we have been improving? could you have been improving? could they have been improving?

Interro-negative form

Simple form	V-ing form
couldn't I improve? couldn't you improve? couldn't he improve? couldn't we improve? couldn't you improve? couldn't they improve?	couldn't I be improving? couldn't you be improving? couldn't he be improving? couldn't we be improving? couldn't you be improving? couldn't they be improving?
Perfect	V-ing perfect
couldn't I have improved? couldn't you have improved? couldn't he have improved? couldn't we have improved? couldn't you have improved? couldn't they have improved?	couldn't I have been improving? couldn't you have been improving? couldn't he have been improving? couldn't we have been improving? couldn't you have been improving? couldn't they have been improving?