could strain
Verbo regular: strain - strained- strained

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I could strain
you could strain
he could strain
we could strain
you could strain
they could strain 	I could be straining
you could be straining
he could be straining
we could be straining
you could be straining
they could be straining	I could have strained
you could have strained
he could have strained
we could have strained
you could have strained
they could have strained	I could have been straining
you could have been straining
he could have been straining
we could have been straining
you could have been straining
they could have been straining	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I couldn't strain
you couldn't strain
he couldn't strain
we couldn't strain
you couldn't strain
they couldn't strain 	I couldn't be straining
you couldn't be straining
he couldn't be straining
we couldn't be straining
you couldn't be straining
they couldn't be straining	I couldn't have strained
you couldn't have strained
he couldn't have strained
we couldn't have strained
you couldn't have strained
they couldn't have strained	I couldn't have been straining
you couldn't have been straining
he couldn't have been straining
we couldn't have been straining
you couldn't have been straining
they couldn't have been straining	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
could I strain?
could you strain?
could he strain?
could we strain?
could you strain?
could they strain? 	could I be straining?
could you be straining?
could he be straining?
could we be straining?
could you be straining?
could they be straining? 	could I have strained?
could you have strained?
could he have strained?
could we have strained?
could you have strained?
could they have strained? 	could I have been straining?
could you have been straining?
could he have been straining?
could we have been straining?
could you have been straining?
could they have been straining? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
couldn't I strain?
couldn't you strain?
couldn't he strain?
couldn't we strain?
couldn't you strain?
couldn't they strain? 	couldn't I be straining?
couldn't you be straining?
couldn't he be straining?
couldn't we be straining?
couldn't you be straining?
couldn't they be straining? 	couldn't I have strained?
couldn't you have strained?
couldn't he have strained?
couldn't we have strained?
couldn't you have strained?
couldn't they have strained? 	couldn't I have been straining?
couldn't you have been straining?
couldn't he have been straining?
couldn't we have been straining?
couldn't you have been straining?
couldn't they have been straining?