must sieve
Verbo regular: sieve - sieved- sieved

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must sieve
you must sieve
he must sieve
we must sieve
you must sieve
they must sieve 	I must be sieving
you must be sieving
he must be sieving
we must be sieving
you must be sieving
they must be sieving	I must have sieved
you must have sieved
he must have sieved
we must have sieved
you must have sieved
they must have sieved	I must have been sieving
you must have been sieving
he must have been sieving
we must have been sieving
you must have been sieving
they must have been sieving	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must not sieve
you must not sieve
he must not sieve
we must not sieve
you must not sieve
they must not sieve 	I must not be sieving
you must not be sieving
he must not be sieving
we must not be sieving
you must not be sieving
they must not be sieving	I must not have sieved
you must not have sieved
he must not have sieved
we must not have sieved
you must not have sieved
they must not have sieved	I must not have been sieving
you must not have been sieving
he must not have been sieving
we must not have been sieving
you must not have been sieving
they must not have been sieving	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I sieve?
must you sieve?
must he sieve?
must we sieve?
must you sieve?
must they sieve? 	must I be sieving?
must you be sieving?
must he be sieving?
must we be sieving?
must you be sieving?
must they be sieving? 	must I have sieved?
must you have sieved?
must he have sieved?
must we have sieved?
must you have sieved?
must they have sieved? 	must I have been sieving?
must you have been sieving?
must he have been sieving?
must we have been sieving?
must you have been sieving?
must they have been sieving? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I not sieve?
must you not sieve?
must he not sieve?
must we not sieve?
must you not sieve?
must they not sieve? 	must I not be sieving?
must you not be sieving?
must he not be sieving?
must we not be sieving?
must you not be sieving?
must they not be sieving? 	must I not have sieved?
must you not have sieved?
must he not have sieved?
must we not have sieved?
must you not have sieved?
must they not have sieved? 	must I not have been sieving?
must you not have been sieving?
must he not have been sieving?
must we not have been sieving?
must you not have been sieving?
must they not have been sieving?