must sip
Regular verb: sip - sipped- sipped

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must sip
you must sip
she must sip
we must sip
you must sip
they must sip 	I must be sipping
you must be sipping
she must be sipping
we must be sipping
you must be sipping
they must be sipping	I must have sipped
you must have sipped
she must have sipped
we must have sipped
you must have sipped
they must have sipped	I must have been sipping
you must have been sipping
she must have been sipping
we must have been sipping
you must have been sipping
they must have been sipping	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't sip
you mustn't sip
she mustn't sip
we mustn't sip
you mustn't sip
they mustn't sip 	I mustn't be sipping
you mustn't be sipping
she mustn't be sipping
we mustn't be sipping
you mustn't be sipping
they mustn't be sipping	I mustn't have sipped
you mustn't have sipped
she mustn't have sipped
we mustn't have sipped
you mustn't have sipped
they mustn't have sipped	I mustn't have been sipping
you mustn't have been sipping
she mustn't have been sipping
we mustn't have been sipping
you mustn't have been sipping
they mustn't have been sipping	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I sip?
must you sip?
must she sip?
must we sip?
must you sip?
must they sip? 	must I be sipping?
must you be sipping?
must she be sipping?
must we be sipping?
must you be sipping?
must they be sipping? 	must I have sipped?
must you have sipped?
must she have sipped?
must we have sipped?
must you have sipped?
must they have sipped? 	must I have been sipping?
must you have been sipping?
must she have been sipping?
must we have been sipping?
must you have been sipping?
must they have been sipping? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I sip?
mustn't you sip?
mustn't she sip?
mustn't we sip?
mustn't you sip?
mustn't they sip? 	mustn't I be sipping?
mustn't you be sipping?
mustn't she be sipping?
mustn't we be sipping?
mustn't you be sipping?
mustn't they be sipping? 	mustn't I have sipped?
mustn't you have sipped?
mustn't she have sipped?
mustn't we have sipped?
mustn't you have sipped?
mustn't they have sipped? 	mustn't I have been sipping?
mustn't you have been sipping?
mustn't she have been sipping?
mustn't we have been sipping?
mustn't you have been sipping?
mustn't they have been sipping?