could succumb
Regular verb: succumb - succumbed- succumbed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could succumb
you could succumb
she could succumb
we could succumb
you could succumb
they could succumb 	I could be succumbing
you could be succumbing
she could be succumbing
we could be succumbing
you could be succumbing
they could be succumbing	I could have succumbed
you could have succumbed
she could have succumbed
we could have succumbed
you could have succumbed
they could have succumbed	I could have been succumbing
you could have been succumbing
she could have been succumbing
we could have been succumbing
you could have been succumbing
they could have been succumbing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not succumb
you could not succumb
she could not succumb
we could not succumb
you could not succumb
they could not succumb 	I could not be succumbing
you could not be succumbing
she could not be succumbing
we could not be succumbing
you could not be succumbing
they could not be succumbing	I could not have succumbed
you could not have succumbed
she could not have succumbed
we could not have succumbed
you could not have succumbed
they could not have succumbed	I could not have been succumbing
you could not have been succumbing
she could not have been succumbing
we could not have been succumbing
you could not have been succumbing
they could not have been succumbing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I succumb?
could you succumb?
could she succumb?
could we succumb?
could you succumb?
could they succumb? 	could I be succumbing?
could you be succumbing?
could she be succumbing?
could we be succumbing?
could you be succumbing?
could they be succumbing? 	could I have succumbed?
could you have succumbed?
could she have succumbed?
could we have succumbed?
could you have succumbed?
could they have succumbed? 	could I have been succumbing?
could you have been succumbing?
could she have been succumbing?
could we have been succumbing?
could you have been succumbing?
could they have been succumbing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not succumb?
could you not succumb?
could she not succumb?
could we not succumb?
could you not succumb?
could they not succumb? 	could I not be succumbing?
could you not be succumbing?
could she not be succumbing?
could we not be succumbing?
could you not be succumbing?
could they not be succumbing? 	could I not have succumbed?
could you not have succumbed?
could she not have succumbed?
could we not have succumbed?
could you not have succumbed?
could they not have succumbed? 	could I not have been succumbing?
could you not have been succumbing?
could she not have been succumbing?
could we not have been succumbing?
could you not have been succumbing?
could they not have been succumbing?