I can improve you can improve he can improve we can improve you can improve they can improve
V-ing form
I can be improving you can be improving he can be improving we can be improving you can be improving they can be improving
Perfect
I can have improved you can have improved he can have improved we can have improved you can have improved they can have improved
V-ing perfect
I can have been improving you can have been improving he can have been improving we can have been improving you can have been improving they can have been improving
Negation
Simple form
I cannot improve you cannot improve he cannot improve we cannot improve you cannot improve they cannot improve
V-ing form
I cannot be improving you cannot be improving he cannot be improving we cannot be improving you cannot be improving they cannot be improving
Perfect
I cannot have improved you cannot have improved he cannot have improved we cannot have improved you cannot have improved they cannot have improved
V-ing perfect
I cannot have been improving you cannot have been improving he cannot have been improving we cannot have been improving you cannot have been improving they cannot have been improving
Interrogative form
Simple form
can I improve? can you improve? can he improve? can we improve? can you improve? can they improve?
V-ing form
can I be improving? can you be improving? can he be improving? can we be improving? can you be improving? can they be improving?
Perfect
can I have improved? can you have improved? can he have improved? can we have improved? can you have improved? can they have improved?
V-ing perfect
can I have been improving? can you have been improving? can he have been improving? can we have been improving? can you have been improving? can they have been improving?
Interro-negative form
Simple form
can I not improve? can you not improve? can he not improve? can we not improve? can you not improve? can they not improve?
V-ing form
can I not be improving? can you not be improving? can he not be improving? can we not be improving? can you not be improving? can they not be improving?
Perfect
can I not have improved? can you not have improved? can he not have improved? can we not have improved? can you not have improved? can they not have improved?
V-ing perfect
can I not have been improving? can you not have been improving? can he not have been improving? can we not have been improving? can you not have been improving? can they not have been improving?