I can stifle you can stifle he can stifle we can stifle you can stifle they can stifle
V-ing form
I can be stifling you can be stifling he can be stifling we can be stifling you can be stifling they can be stifling
Perfect
I can have stifled you can have stifled he can have stifled we can have stifled you can have stifled they can have stifled
V-ing perfect
I can have been stifling you can have been stifling he can have been stifling we can have been stifling you can have been stifling they can have been stifling
Negation
Simple form
I can't stifle you can't stifle he can't stifle we can't stifle you can't stifle they can't stifle
V-ing form
I can't be stifling you can't be stifling he can't be stifling we can't be stifling you can't be stifling they can't be stifling
Perfect
I can't have stifled you can't have stifled he can't have stifled we can't have stifled you can't have stifled they can't have stifled
V-ing perfect
I can't have been stifling you can't have been stifling he can't have been stifling we can't have been stifling you can't have been stifling they can't have been stifling
Interrogative form
Simple form
can I stifle? can you stifle? can he stifle? can we stifle? can you stifle? can they stifle?
V-ing form
can I be stifling? can you be stifling? can he be stifling? can we be stifling? can you be stifling? can they be stifling?
Perfect
can I have stifled? can you have stifled? can he have stifled? can we have stifled? can you have stifled? can they have stifled?
V-ing perfect
can I have been stifling? can you have been stifling? can he have been stifling? can we have been stifling? can you have been stifling? can they have been stifling?
Interro-negative form
Simple form
can't I stifle? can't you stifle? can't he stifle? can't we stifle? can't you stifle? can't they stifle?
V-ing form
can't I be stifling? can't you be stifling? can't he be stifling? can't we be stifling? can't you be stifling? can't they be stifling?
Perfect
can't I have stifled? can't you have stifled? can't he have stifled? can't we have stifled? can't you have stifled? can't they have stifled?
V-ing perfect
can't I have been stifling? can't you have been stifling? can't he have been stifling? can't we have been stifling? can't you have been stifling? can't they have been stifling?