must combine
Regular verb: combine - combined- combined

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must combine
you must combine
she must combine
we must combine
you must combine
they must combine 	I must be combining
you must be combining
she must be combining
we must be combining
you must be combining
they must be combining	I must have combined
you must have combined
she 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
she 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
she 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
she 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
she 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
she 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 she combine?
must we combine?
must you combine?
must they combine? 	must I be combining?
must you be combining?
must she be combining?
must we be combining?
must you be combining?
must they be combining? 	must I have combined?
must you have combined?
must she 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 she 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 she 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 she 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 she 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 she have been combining?
mustn't we have been combining?
mustn't you have been combining?
mustn't they have been combining?