could lock
Verbo regular: lock - locked- locked

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I could lock
you could lock
he could lock
we could lock
you could lock
they could lock 	I could be locking
you could be locking
he could be locking
we could be locking
you could be locking
they could be locking	I could have locked
you could have locked
he could have locked
we could have locked
you could have locked
they could have locked	I could have been locking
you could have been locking
he could have been locking
we could have been locking
you could have been locking
they could have been locking	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I couldn't lock
you couldn't lock
he couldn't lock
we couldn't lock
you couldn't lock
they couldn't lock 	I couldn't be locking
you couldn't be locking
he couldn't be locking
we couldn't be locking
you couldn't be locking
they couldn't be locking	I couldn't have locked
you couldn't have locked
he couldn't have locked
we couldn't have locked
you couldn't have locked
they couldn't have locked	I couldn't have been locking
you couldn't have been locking
he couldn't have been locking
we couldn't have been locking
you couldn't have been locking
they couldn't have been locking	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
could I lock?
could you lock?
could he lock?
could we lock?
could you lock?
could they lock? 	could I be locking?
could you be locking?
could he be locking?
could we be locking?
could you be locking?
could they be locking? 	could I have locked?
could you have locked?
could he have locked?
could we have locked?
could you have locked?
could they have locked? 	could I have been locking?
could you have been locking?
could he have been locking?
could we have been locking?
could you have been locking?
could they have been locking? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
couldn't I lock?
couldn't you lock?
couldn't he lock?
couldn't we lock?
couldn't you lock?
couldn't they lock? 	couldn't I be locking?
couldn't you be locking?
couldn't he be locking?
couldn't we be locking?
couldn't you be locking?
couldn't they be locking? 	couldn't I have locked?
couldn't you have locked?
couldn't he have locked?
couldn't we have locked?
couldn't you have locked?
couldn't they have locked? 	couldn't I have been locking?
couldn't you have been locking?
couldn't he have been locking?
couldn't we have been locking?
couldn't you have been locking?
couldn't they have been locking?