I can busk you can busk he can busk we can busk you can busk they can busk
V-ing form
I can be busking you can be busking he can be busking we can be busking you can be busking they can be busking
Perfect
I can have busked you can have busked he 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 he can have been busking we can have been busking you can have been busking they can have been busking
Negation
Simple form
I can't busk you can't busk he can't busk we can't busk you can't busk they can't busk
V-ing form
I can't be busking you can't be busking he can't be busking we can't be busking you can't be busking they can't be busking
Perfect
I can't have busked you can't have busked he can't have busked we can't have busked you can't have busked they can't have busked
V-ing perfect
I can't have been busking you can't have been busking he can't have been busking we can't have been busking you can't have been busking they can't have been busking
Interrogative form
Simple form
can I busk? can you busk? can he busk? can we busk? can you busk? can they busk?
V-ing form
can I be busking? can you be busking? can he be busking? can we be busking? can you be busking? can they be busking?
Perfect
can I have busked? can you have busked? can he 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 he have been busking? can we have been busking? can you have been busking? can they have been busking?
Interro-negative form
Simple form
can't I busk? can't you busk? can't he busk? can't we busk? can't you busk? can't they busk?
V-ing form
can't I be busking? can't you be busking? can't he be busking? can't we be busking? can't you be busking? can't they be busking?
Perfect
can't I have busked? can't you have busked? can't he have busked? can't we have busked? can't you have busked? can't they have busked?
V-ing perfect
can't I have been busking? can't you have been busking? can't he have been busking? can't we have been busking? can't you have been busking? can't they have been busking?