should strengthen
Verbo regular: strengthen - strengthened- strengthened

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I should strengthen
you should strengthen
he should strengthen
we should strengthen
you should strengthen
they should strengthen 	I should be strengthening
you should be strengthening
he should be strengthening
we should be strengthening
you should be strengthening
they should be strengthening	I should have strengthened
you should have strengthened
he should have strengthened
we should have strengthened
you should have strengthened
they should have strengthened	I should have been strengthening
you should have been strengthening
he should have been strengthening
we should have been strengthening
you should have been strengthening
they should have been strengthening	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I should not strengthen
you should not strengthen
he should not strengthen
we should not strengthen
you should not strengthen
they should not strengthen 	I should not be strengthening
you should not be strengthening
he should not be strengthening
we should not be strengthening
you should not be strengthening
they should not be strengthening	I should not have strengthened
you should not have strengthened
he should not have strengthened
we should not have strengthened
you should not have strengthened
they should not have strengthened	I should not have been strengthening
you should not have been strengthening
he should not have been strengthening
we should not have been strengthening
you should not have been strengthening
they should not have been strengthening	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
should I strengthen?
should you strengthen?
should he strengthen?
should we strengthen?
should you strengthen?
should they strengthen? 	should I be strengthening?
should you be strengthening?
should he be strengthening?
should we be strengthening?
should you be strengthening?
should they be strengthening? 	should I have strengthened?
should you have strengthened?
should he have strengthened?
should we have strengthened?
should you have strengthened?
should they have strengthened? 	should I have been strengthening?
should you have been strengthening?
should he have been strengthening?
should we have been strengthening?
should you have been strengthening?
should they have been strengthening? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
should I not strengthen?
should you not strengthen?
should he not strengthen?
should we not strengthen?
should you not strengthen?
should they not strengthen? 	should I not be strengthening?
should you not be strengthening?
should he not be strengthening?
should we not be strengthening?
should you not be strengthening?
should they not be strengthening? 	should I not have strengthened?
should you not have strengthened?
should he not have strengthened?
should we not have strengthened?
should you not have strengthened?
should they not have strengthened? 	should I not have been strengthening?
should you not have been strengthening?
should he not have been strengthening?
should we not have been strengthening?
should you not have been strengthening?
should they not have been strengthening?