must crack
Verbo regular: crack - cracked- cracked

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must crack
you must crack
she must crack
we must crack
you must crack
they must crack 	I must be cracking
you must be cracking
she must be cracking
we must be cracking
you must be cracking
they must be cracking	I must have cracked
you must have cracked
she must have cracked
we must have cracked
you must have cracked
they must have cracked	I must have been cracking
you must have been cracking
she must have been cracking
we must have been cracking
you must have been cracking
they must have been cracking	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must not crack
you must not crack
she must not crack
we must not crack
you must not crack
they must not crack 	I must not be cracking
you must not be cracking
she must not be cracking
we must not be cracking
you must not be cracking
they must not be cracking	I must not have cracked
you must not have cracked
she must not have cracked
we must not have cracked
you must not have cracked
they must not have cracked	I must not have been cracking
you must not have been cracking
she must not have been cracking
we must not have been cracking
you must not have been cracking
they must not have been cracking	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I crack?
must you crack?
must she crack?
must we crack?
must you crack?
must they crack? 	must I be cracking?
must you be cracking?
must she be cracking?
must we be cracking?
must you be cracking?
must they be cracking? 	must I have cracked?
must you have cracked?
must she have cracked?
must we have cracked?
must you have cracked?
must they have cracked? 	must I have been cracking?
must you have been cracking?
must she have been cracking?
must we have been cracking?
must you have been cracking?
must they have been cracking? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I not crack?
must you not crack?
must she not crack?
must we not crack?
must you not crack?
must they not crack? 	must I not be cracking?
must you not be cracking?
must she not be cracking?
must we not be cracking?
must you not be cracking?
must they not be cracking? 	must I not have cracked?
must you not have cracked?
must she not have cracked?
must we not have cracked?
must you not have cracked?
must they not have cracked? 	must I not have been cracking?
must you not have been cracking?
must she not have been cracking?
must we not have been cracking?
must you not have been cracking?
must they not have been cracking?