can investigate
Regular verb: investigate - investigated- investigated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can investigate
you can investigate
she can investigate
we can investigate
you can investigate
they can investigate 	I can be investigating
you can be investigating
she can be investigating
we can be investigating
you can be investigating
they can be investigating	I can have investigated
you can have investigated
she can have investigated
we can have investigated
you can have investigated
they can have investigated	I can have been investigating
you can have been investigating
she can have been investigating
we can have been investigating
you can have been investigating
they can have been investigating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I cannot investigate
you cannot investigate
she cannot investigate
we cannot investigate
you cannot investigate
they cannot investigate 	I cannot be investigating
you cannot be investigating
she cannot be investigating
we cannot be investigating
you cannot be investigating
they cannot be investigating	I cannot have investigated
you cannot have investigated
she cannot have investigated
we cannot have investigated
you cannot have investigated
they cannot have investigated	I cannot have been investigating
you cannot have been investigating
she cannot have been investigating
we cannot have been investigating
you cannot have been investigating
they cannot have been investigating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I investigate?
can you investigate?
can she investigate?
can we investigate?
can you investigate?
can they investigate? 	can I be investigating?
can you be investigating?
can she be investigating?
can we be investigating?
can you be investigating?
can they be investigating? 	can I have investigated?
can you have investigated?
can she have investigated?
can we have investigated?
can you have investigated?
can they have investigated? 	can I have been investigating?
can you have been investigating?
can she have been investigating?
can we have been investigating?
can you have been investigating?
can they have been investigating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I not investigate?
can you not investigate?
can she not investigate?
can we not investigate?
can you not investigate?
can they not investigate? 	can I not be investigating?
can you not be investigating?
can she not be investigating?
can we not be investigating?
can you not be investigating?
can they not be investigating? 	can I not have investigated?
can you not have investigated?
can she not have investigated?
can we not have investigated?
can you not have investigated?
can they not have investigated? 	can I not have been investigating?
can you not have been investigating?
can she not have been investigating?
can we not have been investigating?
can you not have been investigating?
can they not have been investigating?