could overnight
Regular verb: overnight - overnighted- overnighted

Affirmation 	
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I could overnight
you could overnight
she could overnight
we could overnight
you could overnight
they could overnight 	I could be overnighting
you could be overnighting
she could be overnighting
we could be overnighting
you could be overnighting
they could be overnighting	I could have overnighted
you could have overnighted
she could have overnighted
we could have overnighted
you could have overnighted
they could have overnighted	I could have been overnighting
you could have been overnighting
she could have been overnighting
we could have been overnighting
you could have been overnighting
they could have been overnighting	

Negation 	
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I couldn't overnight
you couldn't overnight
she couldn't overnight
we couldn't overnight
you couldn't overnight
they couldn't overnight 	I couldn't be overnighting
you couldn't be overnighting
she couldn't be overnighting
we couldn't be overnighting
you couldn't be overnighting
they couldn't be overnighting	I couldn't have overnighted
you couldn't have overnighted
she couldn't have overnighted
we couldn't have overnighted
you couldn't have overnighted
they couldn't have overnighted	I couldn't have been overnighting
you couldn't have been overnighting
she couldn't have been overnighting
we couldn't have been overnighting
you couldn't have been overnighting
they couldn't have been overnighting	

Interrogative form 	
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could I overnight?
could you overnight?
could she overnight?
could we overnight?
could you overnight?
could they overnight? 	could I be overnighting?
could you be overnighting?
could she be overnighting?
could we be overnighting?
could you be overnighting?
could they be overnighting? 	could I have overnighted?
could you have overnighted?
could she have overnighted?
could we have overnighted?
could you have overnighted?
could they have overnighted? 	could I have been overnighting?
could you have been overnighting?
could she have been overnighting?
could we have been overnighting?
could you have been overnighting?
could they have been overnighting? 	

Interro-negative form 	
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couldn't I overnight?
couldn't you overnight?
couldn't she overnight?
couldn't we overnight?
couldn't you overnight?
couldn't they overnight? 	couldn't I be overnighting?
couldn't you be overnighting?
couldn't she be overnighting?
couldn't we be overnighting?
couldn't you be overnighting?
couldn't they be overnighting? 	couldn't I have overnighted?
couldn't you have overnighted?
couldn't she have overnighted?
couldn't we have overnighted?
couldn't you have overnighted?
couldn't they have overnighted? 	couldn't I have been overnighting?
couldn't you have been overnighting?
couldn't she have been overnighting?
couldn't we have been overnighting?
couldn't you have been overnighting?
couldn't they have been overnighting?