I can string you can string she can string we can string you can string they can string
V-ing form
I can be stringing you can be stringing she can be stringing we can be stringing you can be stringing they can be stringing
Perfect
I can have strung you can have strung she can have strung we can have strung you can have strung they can have strung
V-ing perfect
I can have been stringing you can have been stringing she can have been stringing we can have been stringing you can have been stringing they can have been stringing
Negation
Simple form
I cannot string you cannot string she cannot string we cannot string you cannot string they cannot string
V-ing form
I cannot be stringing you cannot be stringing she cannot be stringing we cannot be stringing you cannot be stringing they cannot be stringing
Perfect
I cannot have strung you cannot have strung she cannot have strung we cannot have strung you cannot have strung they cannot have strung
V-ing perfect
I cannot have been stringing you cannot have been stringing she cannot have been stringing we cannot have been stringing you cannot have been stringing they cannot have been stringing
Interrogative form
Simple form
can I string? can you string? can she string? can we string? can you string? can they string?
V-ing form
can I be stringing? can you be stringing? can she be stringing? can we be stringing? can you be stringing? can they be stringing?
Perfect
can I have strung? can you have strung? can she have strung? can we have strung? can you have strung? can they have strung?
V-ing perfect
can I have been stringing? can you have been stringing? can she have been stringing? can we have been stringing? can you have been stringing? can they have been stringing?
Interro-negative form
Simple form
can I not string? can you not string? can she not string? can we not string? can you not string? can they not string?
V-ing form
can I not be stringing? can you not be stringing? can she not be stringing? can we not be stringing? can you not be stringing? can they not be stringing?
Perfect
can I not have strung? can you not have strung? can she not have strung? can we not have strung? can you not have strung? can they not have strung?
V-ing perfect
can I not have been stringing? can you not have been stringing? can she not have been stringing? can we not have been stringing? can you not have been stringing? can they not have been stringing?