can stem
Verbo regular: stem - stemmed- stemmed

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I can stem
you can stem
he can stem
we can stem
you can stem
they can stem 	I can be stemming
you can be stemming
he can be stemming
we can be stemming
you can be stemming
they can be stemming	I can have stemmed
you can have stemmed
he can have stemmed
we can have stemmed
you can have stemmed
they can have stemmed	I can have been stemming
you can have been stemming
he can have been stemming
we can have been stemming
you can have been stemming
they can have been stemming	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I can't stem
you can't stem
he can't stem
we can't stem
you can't stem
they can't stem 	I can't be stemming
you can't be stemming
he can't be stemming
we can't be stemming
you can't be stemming
they can't be stemming	I can't have stemmed
you can't have stemmed
he can't have stemmed
we can't have stemmed
you can't have stemmed
they can't have stemmed	I can't have been stemming
you can't have been stemming
he can't have been stemming
we can't have been stemming
you can't have been stemming
they can't have been stemming	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
can I stem?
can you stem?
can he stem?
can we stem?
can you stem?
can they stem? 	can I be stemming?
can you be stemming?
can he be stemming?
can we be stemming?
can you be stemming?
can they be stemming? 	can I have stemmed?
can you have stemmed?
can he have stemmed?
can we have stemmed?
can you have stemmed?
can they have stemmed? 	can I have been stemming?
can you have been stemming?
can he have been stemming?
can we have been stemming?
can you have been stemming?
can they have been stemming? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
can't I stem?
can't you stem?
can't he stem?
can't we stem?
can't you stem?
can't they stem? 	can't I be stemming?
can't you be stemming?
can't he be stemming?
can't we be stemming?
can't you be stemming?
can't they be stemming? 	can't I have stemmed?
can't you have stemmed?
can't he have stemmed?
can't we have stemmed?
can't you have stemmed?
can't they have stemmed? 	can't I have been stemming?
can't you have been stemming?
can't he have been stemming?
can't we have been stemming?
can't you have been stemming?
can't they have been stemming?