must yack
Verbo regular: yack - yacked- yacked

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must yack
you must yack
he must yack
we must yack
you must yack
they must yack 	I must be yacking
you must be yacking
he must be yacking
we must be yacking
you must be yacking
they must be yacking	I must have yacked
you must have yacked
he must have yacked
we must have yacked
you must have yacked
they must have yacked	I must have been yacking
you must have been yacking
he must have been yacking
we must have been yacking
you must have been yacking
they must have been yacking	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must not yack
you must not yack
he must not yack
we must not yack
you must not yack
they must not yack 	I must not be yacking
you must not be yacking
he must not be yacking
we must not be yacking
you must not be yacking
they must not be yacking	I must not have yacked
you must not have yacked
he must not have yacked
we must not have yacked
you must not have yacked
they must not have yacked	I must not have been yacking
you must not have been yacking
he must not have been yacking
we must not have been yacking
you must not have been yacking
they must not have been yacking	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I yack?
must you yack?
must he yack?
must we yack?
must you yack?
must they yack? 	must I be yacking?
must you be yacking?
must he be yacking?
must we be yacking?
must you be yacking?
must they be yacking? 	must I have yacked?
must you have yacked?
must he have yacked?
must we have yacked?
must you have yacked?
must they have yacked? 	must I have been yacking?
must you have been yacking?
must he have been yacking?
must we have been yacking?
must you have been yacking?
must they have been yacking? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I not yack?
must you not yack?
must he not yack?
must we not yack?
must you not yack?
must they not yack? 	must I not be yacking?
must you not be yacking?
must he not be yacking?
must we not be yacking?
must you not be yacking?
must they not be yacking? 	must I not have yacked?
must you not have yacked?
must he not have yacked?
must we not have yacked?
must you not have yacked?
must they not have yacked? 	must I not have been yacking?
must you not have been yacking?
must he not have been yacking?
must we not have been yacking?
must you not have been yacking?
must they not have been yacking?