could start
Regular verb: start - started- started

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could start
you could start
he could start
we could start
you could start
they could start 	I could be starting
you could be starting
he could be starting
we could be starting
you could be starting
they could be starting	I could have started
you could have started
he could have started
we could have started
you could have started
they could have started	I could have been starting
you could have been starting
he could have been starting
we could have been starting
you could have been starting
they could have been starting	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not start
you could not start
he could not start
we could not start
you could not start
they could not start 	I could not be starting
you could not be starting
he could not be starting
we could not be starting
you could not be starting
they could not be starting	I could not have started
you could not have started
he could not have started
we could not have started
you could not have started
they could not have started	I could not have been starting
you could not have been starting
he could not have been starting
we could not have been starting
you could not have been starting
they could not have been starting	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I start?
could you start?
could he start?
could we start?
could you start?
could they start? 	could I be starting?
could you be starting?
could he be starting?
could we be starting?
could you be starting?
could they be starting? 	could I have started?
could you have started?
could he have started?
could we have started?
could you have started?
could they have started? 	could I have been starting?
could you have been starting?
could he have been starting?
could we have been starting?
could you have been starting?
could they have been starting? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not start?
could you not start?
could he not start?
could we not start?
could you not start?
could they not start? 	could I not be starting?
could you not be starting?
could he not be starting?
could we not be starting?
could you not be starting?
could they not be starting? 	could I not have started?
could you not have started?
could he not have started?
could we not have started?
could you not have started?
could they not have started? 	could I not have been starting?
could you not have been starting?
could he not have been starting?
could we not have been starting?
could you not have been starting?
could they not have been starting?