may toughen
Regular verb: toughen - toughened- toughened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I may toughen
you may toughen
she may toughen
we may toughen
you may toughen
they may toughen 	I may be toughening
you may be toughening
she may be toughening
we may be toughening
you may be toughening
they may be toughening	I may have toughened
you may have toughened
she may have toughened
we may have toughened
you may have toughened
they may have toughened	I may have been toughening
you may have been toughening
she may have been toughening
we may have been toughening
you may have been toughening
they may have been toughening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I may not toughen
you may not toughen
she may not toughen
we may not toughen
you may not toughen
they may not toughen 	I may not be toughening
you may not be toughening
she may not be toughening
we may not be toughening
you may not be toughening
they may not be toughening	I may not have toughened
you may not have toughened
she may not have toughened
we may not have toughened
you may not have toughened
they may not have toughened	I may not have been toughening
you may not have been toughening
she may not have been toughening
we may not have been toughening
you may not have been toughening
they may not have been toughening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
may I toughen?
may you toughen?
may she toughen?
may we toughen?
may you toughen?
may they toughen? 	may I be toughening?
may you be toughening?
may she be toughening?
may we be toughening?
may you be toughening?
may they be toughening? 	may I have toughened?
may you have toughened?
may she have toughened?
may we have toughened?
may you have toughened?
may they have toughened? 	may I have been toughening?
may you have been toughening?
may she have been toughening?
may we have been toughening?
may you have been toughening?
may they have been toughening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
may I not toughen?
may you not toughen?
may she not toughen?
may we not toughen?
may you not toughen?
may they not toughen? 	may I not be toughening?
may you not be toughening?
may she not be toughening?
may we not be toughening?
may you not be toughening?
may they not be toughening? 	may I not have toughened?
may you not have toughened?
may she not have toughened?
may we not have toughened?
may you not have toughened?
may they not have toughened? 	may I not have been toughening?
may you not have been toughening?
may she not have been toughening?
may we not have been toughening?
may you not have been toughening?
may they not have been toughening?