can constrain
Regular verb: constrain - constrained- constrained

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can constrain
you can constrain
he can constrain
we can constrain
you can constrain
they can constrain 	I can be constraining
you can be constraining
he can be constraining
we can be constraining
you can be constraining
they can be constraining	I can have constrained
you can have constrained
he can have constrained
we can have constrained
you can have constrained
they can have constrained	I can have been constraining
you can have been constraining
he can have been constraining
we can have been constraining
you can have been constraining
they can have been constraining	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I cannot constrain
you cannot constrain
he cannot constrain
we cannot constrain
you cannot constrain
they cannot constrain 	I cannot be constraining
you cannot be constraining
he cannot be constraining
we cannot be constraining
you cannot be constraining
they cannot be constraining	I cannot have constrained
you cannot have constrained
he cannot have constrained
we cannot have constrained
you cannot have constrained
they cannot have constrained	I cannot have been constraining
you cannot have been constraining
he cannot have been constraining
we cannot have been constraining
you cannot have been constraining
they cannot have been constraining	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I constrain?
can you constrain?
can he constrain?
can we constrain?
can you constrain?
can they constrain? 	can I be constraining?
can you be constraining?
can he be constraining?
can we be constraining?
can you be constraining?
can they be constraining? 	can I have constrained?
can you have constrained?
can he have constrained?
can we have constrained?
can you have constrained?
can they have constrained? 	can I have been constraining?
can you have been constraining?
can he have been constraining?
can we have been constraining?
can you have been constraining?
can they have been constraining? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I not constrain?
can you not constrain?
can he not constrain?
can we not constrain?
can you not constrain?
can they not constrain? 	can I not be constraining?
can you not be constraining?
can he not be constraining?
can we not be constraining?
can you not be constraining?
can they not be constraining? 	can I not have constrained?
can you not have constrained?
can he not have constrained?
can we not have constrained?
can you not have constrained?
can they not have constrained? 	can I not have been constraining?
can you not have been constraining?
can he not have been constraining?
can we not have been constraining?
can you not have been constraining?
can they not have been constraining?