I could improve you could improve he could improve we could improve you could improve they could improve
Forma con V-ing
I could be improving you could be improving he could be improving we could be improving you could be improving they could be improving
Perfecto
I could have improved you could have improved he could have improved we could have improved you could have improved they could have improved
Perfecto con V-ing
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
Negación
Forma simple
I couldn't improve you couldn't improve he couldn't improve we couldn't improve you couldn't improve they couldn't improve
Forma con V-ing
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
Perfecto
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
Perfecto con V-ing
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
Forma interrogativa
Forma simple
could I improve? could you improve? could he improve? could we improve? could you improve? could they improve?
Forma con V-ing
could I be improving? could you be improving? could he be improving? could we be improving? could you be improving? could they be improving?
Perfecto
could I have improved? could you have improved? could he have improved? could we have improved? could you have improved? could they have improved?
Perfecto con V-ing
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?
Forma interro-negativa
Forma simple
couldn't I improve? couldn't you improve? couldn't he improve? couldn't we improve? couldn't you improve? couldn't they improve?
Forma con V-ing
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?
Perfecto
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?
Perfecto con V-ing
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?