could cross-check
Regular verb: cross-check - cross-checked- cross-checked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could cross-check
you could cross-check
he could cross-check
we could cross-check
you could cross-check
they could cross-check 	I could be cross-checking
you could be cross-checking
he could be cross-checking
we could be cross-checking
you could be cross-checking
they could be cross-checking	I could have cross-checked
you could have cross-checked
he could have cross-checked
we could have cross-checked
you could have cross-checked
they could have cross-checked	I could have been cross-checking
you could have been cross-checking
he could have been cross-checking
we could have been cross-checking
you could have been cross-checking
they could have been cross-checking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't cross-check
you couldn't cross-check
he couldn't cross-check
we couldn't cross-check
you couldn't cross-check
they couldn't cross-check 	I couldn't be cross-checking
you couldn't be cross-checking
he couldn't be cross-checking
we couldn't be cross-checking
you couldn't be cross-checking
they couldn't be cross-checking	I couldn't have cross-checked
you couldn't have cross-checked
he couldn't have cross-checked
we couldn't have cross-checked
you couldn't have cross-checked
they couldn't have cross-checked	I couldn't have been cross-checking
you couldn't have been cross-checking
he couldn't have been cross-checking
we couldn't have been cross-checking
you couldn't have been cross-checking
they couldn't have been cross-checking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I cross-check?
could you cross-check?
could he cross-check?
could we cross-check?
could you cross-check?
could they cross-check? 	could I be cross-checking?
could you be cross-checking?
could he be cross-checking?
could we be cross-checking?
could you be cross-checking?
could they be cross-checking? 	could I have cross-checked?
could you have cross-checked?
could he have cross-checked?
could we have cross-checked?
could you have cross-checked?
could they have cross-checked? 	could I have been cross-checking?
could you have been cross-checking?
could he have been cross-checking?
could we have been cross-checking?
could you have been cross-checking?
could they have been cross-checking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I cross-check?
couldn't you cross-check?
couldn't he cross-check?
couldn't we cross-check?
couldn't you cross-check?
couldn't they cross-check? 	couldn't I be cross-checking?
couldn't you be cross-checking?
couldn't he be cross-checking?
couldn't we be cross-checking?
couldn't you be cross-checking?
couldn't they be cross-checking? 	couldn't I have cross-checked?
couldn't you have cross-checked?
couldn't he have cross-checked?
couldn't we have cross-checked?
couldn't you have cross-checked?
couldn't they have cross-checked? 	couldn't I have been cross-checking?
couldn't you have been cross-checking?
couldn't he have been cross-checking?
couldn't we have been cross-checking?
couldn't you have been cross-checking?
couldn't they have been cross-checking?