must investigate
Verbo regular: investigate - investigated- investigated

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must investigate
you must investigate
he must investigate
we must investigate
you must investigate
they must investigate 	I must be investigating
you must be investigating
he must be investigating
we must be investigating
you must be investigating
they must be investigating	I must have investigated
you must have investigated
he must have investigated
we must have investigated
you must have investigated
they must have investigated	I must have been investigating
you must have been investigating
he must have been investigating
we must have been investigating
you must have been investigating
they must have been investigating	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I must not investigate
you must not investigate
he must not investigate
we must not investigate
you must not investigate
they must not investigate 	I must not be investigating
you must not be investigating
he must not be investigating
we must not be investigating
you must not be investigating
they must not be investigating	I must not have investigated
you must not have investigated
he must not have investigated
we must not have investigated
you must not have investigated
they must not have investigated	I must not have been investigating
you must not have been investigating
he must not have been investigating
we must not have been investigating
you must not have been investigating
they must not have been investigating	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I investigate?
must you investigate?
must he investigate?
must we investigate?
must you investigate?
must they investigate? 	must I be investigating?
must you be investigating?
must he be investigating?
must we be investigating?
must you be investigating?
must they be investigating? 	must I have investigated?
must you have investigated?
must he have investigated?
must we have investigated?
must you have investigated?
must they have investigated? 	must I have been investigating?
must you have been investigating?
must he have been investigating?
must we have been investigating?
must you have been investigating?
must they have been investigating? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
must I not investigate?
must you not investigate?
must he not investigate?
must we not investigate?
must you not investigate?
must they not investigate? 	must I not be investigating?
must you not be investigating?
must he not be investigating?
must we not be investigating?
must you not be investigating?
must they not be investigating? 	must I not have investigated?
must you not have investigated?
must he not have investigated?
must we not have investigated?
must you not have investigated?
must they not have investigated? 	must I not have been investigating?
must you not have been investigating?
must he not have been investigating?
must we not have been investigating?
must you not have been investigating?
must they not have been investigating?