I can busk you can busk she can busk we can busk you can busk they can busk
V-ing form
I can be busking you can be busking she can be busking we can be busking you can be busking they can be busking
Perfect
I can have busked you can have busked she can have busked we can have busked you can have busked they can have busked
V-ing perfect
I can have been busking you can have been busking she can have been busking we can have been busking you can have been busking they can have been busking
Negation
Simple form
I cannot busk you cannot busk she cannot busk we cannot busk you cannot busk they cannot busk
V-ing form
I cannot be busking you cannot be busking she cannot be busking we cannot be busking you cannot be busking they cannot be busking
Perfect
I cannot have busked you cannot have busked she cannot have busked we cannot have busked you cannot have busked they cannot have busked
V-ing perfect
I cannot have been busking you cannot have been busking she cannot have been busking we cannot have been busking you cannot have been busking they cannot have been busking
Interrogative form
Simple form
can I busk? can you busk? can she busk? can we busk? can you busk? can they busk?
V-ing form
can I be busking? can you be busking? can she be busking? can we be busking? can you be busking? can they be busking?
Perfect
can I have busked? can you have busked? can she have busked? can we have busked? can you have busked? can they have busked?
V-ing perfect
can I have been busking? can you have been busking? can she have been busking? can we have been busking? can you have been busking? can they have been busking?
Interro-negative form
Simple form
can I not busk? can you not busk? can she not busk? can we not busk? can you not busk? can they not busk?
V-ing form
can I not be busking? can you not be busking? can she not be busking? can we not be busking? can you not be busking? can they not be busking?
Perfect
can I not have busked? can you not have busked? can she not have busked? can we not have busked? can you not have busked? can they not have busked?
V-ing perfect
can I not have been busking? can you not have been busking? can she not have been busking? can we not have been busking? can you not have been busking? can they not have been busking?