I can tow you can tow he can tow we can tow you can tow they can tow
V-ing form
I can be towing you can be towing he can be towing we can be towing you can be towing they can be towing
Perfect
I can have towed you can have towed he can have towed we can have towed you can have towed they can have towed
V-ing perfect
I can have been towing you can have been towing he can have been towing we can have been towing you can have been towing they can have been towing
Negation
Simple form
I can't tow you can't tow he can't tow we can't tow you can't tow they can't tow
V-ing form
I can't be towing you can't be towing he can't be towing we can't be towing you can't be towing they can't be towing
Perfect
I can't have towed you can't have towed he can't have towed we can't have towed you can't have towed they can't have towed
V-ing perfect
I can't have been towing you can't have been towing he can't have been towing we can't have been towing you can't have been towing they can't have been towing
Interrogative form
Simple form
can I tow? can you tow? can he tow? can we tow? can you tow? can they tow?
V-ing form
can I be towing? can you be towing? can he be towing? can we be towing? can you be towing? can they be towing?
Perfect
can I have towed? can you have towed? can he have towed? can we have towed? can you have towed? can they have towed?
V-ing perfect
can I have been towing? can you have been towing? can he have been towing? can we have been towing? can you have been towing? can they have been towing?
Interro-negative form
Simple form
can't I tow? can't you tow? can't he tow? can't we tow? can't you tow? can't they tow?
V-ing form
can't I be towing? can't you be towing? can't he be towing? can't we be towing? can't you be towing? can't they be towing?
Perfect
can't I have towed? can't you have towed? can't he have towed? can't we have towed? can't you have towed? can't they have towed?
V-ing perfect
can't I have been towing? can't you have been towing? can't he have been towing? can't we have been towing? can't you have been towing? can't they have been towing?