can sustain
Regular verb: sustain - sustained- sustained

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can sustain
you can sustain
she can sustain
we can sustain
you can sustain
they can sustain 	I can be sustaining
you can be sustaining
she can be sustaining
we can be sustaining
you can be sustaining
they can be sustaining	I can have sustained
you can have sustained
she can have sustained
we can have sustained
you can have sustained
they can have sustained	I can have been sustaining
you can have been sustaining
she can have been sustaining
we can have been sustaining
you can have been sustaining
they can have been sustaining	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can't sustain
you can't sustain
she can't sustain
we can't sustain
you can't sustain
they can't sustain 	I can't be sustaining
you can't be sustaining
she can't be sustaining
we can't be sustaining
you can't be sustaining
they can't be sustaining	I can't have sustained
you can't have sustained
she can't have sustained
we can't have sustained
you can't have sustained
they can't have sustained	I can't have been sustaining
you can't have been sustaining
she can't have been sustaining
we can't have been sustaining
you can't have been sustaining
they can't have been sustaining	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I sustain?
can you sustain?
can she sustain?
can we sustain?
can you sustain?
can they sustain? 	can I be sustaining?
can you be sustaining?
can she be sustaining?
can we be sustaining?
can you be sustaining?
can they be sustaining? 	can I have sustained?
can you have sustained?
can she have sustained?
can we have sustained?
can you have sustained?
can they have sustained? 	can I have been sustaining?
can you have been sustaining?
can she have been sustaining?
can we have been sustaining?
can you have been sustaining?
can they have been sustaining? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can't I sustain?
can't you sustain?
can't she sustain?
can't we sustain?
can't you sustain?
can't they sustain? 	can't I be sustaining?
can't you be sustaining?
can't she be sustaining?
can't we be sustaining?
can't you be sustaining?
can't they be sustaining? 	can't I have sustained?
can't you have sustained?
can't she have sustained?
can't we have sustained?
can't you have sustained?
can't they have sustained? 	can't I have been sustaining?
can't you have been sustaining?
can't she have been sustaining?
can't we have been sustaining?
can't you have been sustaining?
can't they have been sustaining?