must combine
Regular verb: combine - combined- combined

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must combine
you must combine
he must combine
we must combine
you must combine
they must combine 	I must be combining
you must be combining
he must be combining
we must be combining
you must be combining
they must be combining	I must have combined
you must have combined
he must have combined
we must have combined
you must have combined
they must have combined	I must have been combining
you must have been combining
he must have been combining
we must have been combining
you must have been combining
they must have been combining	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't combine
you mustn't combine
he mustn't combine
we mustn't combine
you mustn't combine
they mustn't combine 	I mustn't be combining
you mustn't be combining
he mustn't be combining
we mustn't be combining
you mustn't be combining
they mustn't be combining	I mustn't have combined
you mustn't have combined
he mustn't have combined
we mustn't have combined
you mustn't have combined
they mustn't have combined	I mustn't have been combining
you mustn't have been combining
he mustn't have been combining
we mustn't have been combining
you mustn't have been combining
they mustn't have been combining	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I combine?
must you combine?
must he combine?
must we combine?
must you combine?
must they combine? 	must I be combining?
must you be combining?
must he be combining?
must we be combining?
must you be combining?
must they be combining? 	must I have combined?
must you have combined?
must he have combined?
must we have combined?
must you have combined?
must they have combined? 	must I have been combining?
must you have been combining?
must he have been combining?
must we have been combining?
must you have been combining?
must they have been combining? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I combine?
mustn't you combine?
mustn't he combine?
mustn't we combine?
mustn't you combine?
mustn't they combine? 	mustn't I be combining?
mustn't you be combining?
mustn't he be combining?
mustn't we be combining?
mustn't you be combining?
mustn't they be combining? 	mustn't I have combined?
mustn't you have combined?
mustn't he have combined?
mustn't we have combined?
mustn't you have combined?
mustn't they have combined? 	mustn't I have been combining?
mustn't you have been combining?
mustn't he have been combining?
mustn't we have been combining?
mustn't you have been combining?
mustn't they have been combining?