can investigate
Regular verb: investigate - investigated- investigated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can investigate
you can investigate
he can investigate
we can investigate
you can investigate
they can investigate 	I can be investigating
you can be investigating
he can be investigating
we can be investigating
you can be investigating
they can be investigating	I can have investigated
you can have investigated
he 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
he 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 can't investigate
you can't investigate
he can't investigate
we can't investigate
you can't investigate
they can't investigate 	I can't be investigating
you can't be investigating
he can't be investigating
we can't be investigating
you can't be investigating
they can't be investigating	I can't have investigated
you can't have investigated
he can't have investigated
we can't have investigated
you can't have investigated
they can't have investigated	I can't have been investigating
you can't have been investigating
he can't have been investigating
we can't have been investigating
you can't have been investigating
they can't have been investigating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I investigate?
can you investigate?
can he investigate?
can we investigate?
can you investigate?
can they investigate? 	can I be investigating?
can you be investigating?
can he be investigating?
can we be investigating?
can you be investigating?
can they be investigating? 	can I have investigated?
can you have investigated?
can he 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 he 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't I investigate?
can't you investigate?
can't he investigate?
can't we investigate?
can't you investigate?
can't they investigate? 	can't I be investigating?
can't you be investigating?
can't he be investigating?
can't we be investigating?
can't you be investigating?
can't they be investigating? 	can't I have investigated?
can't you have investigated?
can't he have investigated?
can't we have investigated?
can't you have investigated?
can't they have investigated? 	can't I have been investigating?
can't you have been investigating?
can't he have been investigating?
can't we have been investigating?
can't you have been investigating?
can't they have been investigating?