I can backstroke you can backstroke he can backstroke we can backstroke you can backstroke they can backstroke
V-ing form
I can be backstroking you can be backstroking he can be backstroking we can be backstroking you can be backstroking they can be backstroking
Perfect
I can have backstroked you can have backstroked he can have backstroked we can have backstroked you can have backstroked they can have backstroked
V-ing perfect
I can have been backstroking you can have been backstroking he can have been backstroking we can have been backstroking you can have been backstroking they can have been backstroking
Negation
Simple form
I can't backstroke you can't backstroke he can't backstroke we can't backstroke you can't backstroke they can't backstroke
V-ing form
I can't be backstroking you can't be backstroking he can't be backstroking we can't be backstroking you can't be backstroking they can't be backstroking
Perfect
I can't have backstroked you can't have backstroked he can't have backstroked we can't have backstroked you can't have backstroked they can't have backstroked
V-ing perfect
I can't have been backstroking you can't have been backstroking he can't have been backstroking we can't have been backstroking you can't have been backstroking they can't have been backstroking
Interrogative form
Simple form
can I backstroke? can you backstroke? can he backstroke? can we backstroke? can you backstroke? can they backstroke?
V-ing form
can I be backstroking? can you be backstroking? can he be backstroking? can we be backstroking? can you be backstroking? can they be backstroking?
Perfect
can I have backstroked? can you have backstroked? can he have backstroked? can we have backstroked? can you have backstroked? can they have backstroked?
V-ing perfect
can I have been backstroking? can you have been backstroking? can he have been backstroking? can we have been backstroking? can you have been backstroking? can they have been backstroking?
Interro-negative form
Simple form
can't I backstroke? can't you backstroke? can't he backstroke? can't we backstroke? can't you backstroke? can't they backstroke?
V-ing form
can't I be backstroking? can't you be backstroking? can't he be backstroking? can't we be backstroking? can't you be backstroking? can't they be backstroking?
Perfect
can't I have backstroked? can't you have backstroked? can't he have backstroked? can't we have backstroked? can't you have backstroked? can't they have backstroked?
V-ing perfect
can't I have been backstroking? can't you have been backstroking? can't he have been backstroking? can't we have been backstroking? can't you have been backstroking? can't they have been backstroking?