must suck
Regular verb: suck - sucked- sucked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must suck
you must suck
he must suck
we must suck
you must suck
they must suck 	I must be sucking
you must be sucking
he must be sucking
we must be sucking
you must be sucking
they must be sucking	I must have sucked
you must have sucked
he must have sucked
we must have sucked
you must have sucked
they must have sucked	I must have been sucking
you must have been sucking
he must have been sucking
we must have been sucking
you must have been sucking
they must have been sucking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not suck
you must not suck
he must not suck
we must not suck
you must not suck
they must not suck 	I must not be sucking
you must not be sucking
he must not be sucking
we must not be sucking
you must not be sucking
they must not be sucking	I must not have sucked
you must not have sucked
he must not have sucked
we must not have sucked
you must not have sucked
they must not have sucked	I must not have been sucking
you must not have been sucking
he must not have been sucking
we must not have been sucking
you must not have been sucking
they must not have been sucking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I suck?
must you suck?
must he suck?
must we suck?
must you suck?
must they suck? 	must I be sucking?
must you be sucking?
must he be sucking?
must we be sucking?
must you be sucking?
must they be sucking? 	must I have sucked?
must you have sucked?
must he have sucked?
must we have sucked?
must you have sucked?
must they have sucked? 	must I have been sucking?
must you have been sucking?
must he have been sucking?
must we have been sucking?
must you have been sucking?
must they have been sucking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not suck?
must you not suck?
must he not suck?
must we not suck?
must you not suck?
must they not suck? 	must I not be sucking?
must you not be sucking?
must he not be sucking?
must we not be sucking?
must you not be sucking?
must they not be sucking? 	must I not have sucked?
must you not have sucked?
must he not have sucked?
must we not have sucked?
must you not have sucked?
must they not have sucked? 	must I not have been sucking?
must you not have been sucking?
must he not have been sucking?
must we not have been sucking?
must you not have been sucking?
must they not have been sucking?