must croon
Regular verb: croon - crooned- crooned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must croon
you must croon
he must croon
we must croon
you must croon
they must croon 	I must be crooning
you must be crooning
he must be crooning
we must be crooning
you must be crooning
they must be crooning	I must have crooned
you must have crooned
he must have crooned
we must have crooned
you must have crooned
they must have crooned	I must have been crooning
you must have been crooning
he must have been crooning
we must have been crooning
you must have been crooning
they must have been crooning	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not croon
you must not croon
he must not croon
we must not croon
you must not croon
they must not croon 	I must not be crooning
you must not be crooning
he must not be crooning
we must not be crooning
you must not be crooning
they must not be crooning	I must not have crooned
you must not have crooned
he must not have crooned
we must not have crooned
you must not have crooned
they must not have crooned	I must not have been crooning
you must not have been crooning
he must not have been crooning
we must not have been crooning
you must not have been crooning
they must not have been crooning	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I croon?
must you croon?
must he croon?
must we croon?
must you croon?
must they croon? 	must I be crooning?
must you be crooning?
must he be crooning?
must we be crooning?
must you be crooning?
must they be crooning? 	must I have crooned?
must you have crooned?
must he have crooned?
must we have crooned?
must you have crooned?
must they have crooned? 	must I have been crooning?
must you have been crooning?
must he have been crooning?
must we have been crooning?
must you have been crooning?
must they have been crooning? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not croon?
must you not croon?
must he not croon?
must we not croon?
must you not croon?
must they not croon? 	must I not be crooning?
must you not be crooning?
must he not be crooning?
must we not be crooning?
must you not be crooning?
must they not be crooning? 	must I not have crooned?
must you not have crooned?
must he not have crooned?
must we not have crooned?
must you not have crooned?
must they not have crooned? 	must I not have been crooning?
must you not have been crooning?
must he not have been crooning?
must we not have been crooning?
must you not have been crooning?
must they not have been crooning?