must spring
Verbo irregular: spring - sprang, sprung- sprung

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must spring
you must spring
she must spring
we must spring
you must spring
they must spring 	I must be springing
you must be springing
she must be springing
we must be springing
you must be springing
they must be springing	I must have sprung
you must have sprung
she must have sprung
we must have sprung
you must have sprung
they must have sprung	I must have been springing
you must have been springing
she must have been springing
we must have been springing
you must have been springing
they must have been springing	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I mustn't spring
you mustn't spring
she mustn't spring
we mustn't spring
you mustn't spring
they mustn't spring 	I mustn't be springing
you mustn't be springing
she mustn't be springing
we mustn't be springing
you mustn't be springing
they mustn't be springing	I mustn't have sprung
you mustn't have sprung
she mustn't have sprung
we mustn't have sprung
you mustn't have sprung
they mustn't have sprung	I mustn't have been springing
you mustn't have been springing
she mustn't have been springing
we mustn't have been springing
you mustn't have been springing
they mustn't have been springing	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I spring?
must you spring?
must she spring?
must we spring?
must you spring?
must they spring? 	must I be springing?
must you be springing?
must she be springing?
must we be springing?
must you be springing?
must they be springing? 	must I have sprung?
must you have sprung?
must she have sprung?
must we have sprung?
must you have sprung?
must they have sprung? 	must I have been springing?
must you have been springing?
must she have been springing?
must we have been springing?
must you have been springing?
must they have been springing? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
mustn't I spring?
mustn't you spring?
mustn't she spring?
mustn't we spring?
mustn't you spring?
mustn't they spring? 	mustn't I be springing?
mustn't you be springing?
mustn't she be springing?
mustn't we be springing?
mustn't you be springing?
mustn't they be springing? 	mustn't I have sprung?
mustn't you have sprung?
mustn't she have sprung?
mustn't we have sprung?
mustn't you have sprung?
mustn't they have sprung? 	mustn't I have been springing?
mustn't you have been springing?
mustn't she have been springing?
mustn't we have been springing?
mustn't you have been springing?
mustn't they have been springing?