could grab
Regular verb: grab - grabbed- grabbed

Affirmation 	
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I could grab
you could grab
he could grab
we could grab
you could grab
they could grab 	I could be grabbing
you could be grabbing
he could be grabbing
we could be grabbing
you could be grabbing
they could be grabbing	I could have grabbed
you could have grabbed
he could have grabbed
we could have grabbed
you could have grabbed
they could have grabbed	I could have been grabbing
you could have been grabbing
he could have been grabbing
we could have been grabbing
you could have been grabbing
they could have been grabbing	

Negation 	
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I couldn't grab
you couldn't grab
he couldn't grab
we couldn't grab
you couldn't grab
they couldn't grab 	I couldn't be grabbing
you couldn't be grabbing
he couldn't be grabbing
we couldn't be grabbing
you couldn't be grabbing
they couldn't be grabbing	I couldn't have grabbed
you couldn't have grabbed
he couldn't have grabbed
we couldn't have grabbed
you couldn't have grabbed
they couldn't have grabbed	I couldn't have been grabbing
you couldn't have been grabbing
he couldn't have been grabbing
we couldn't have been grabbing
you couldn't have been grabbing
they couldn't have been grabbing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I grab?
could you grab?
could he grab?
could we grab?
could you grab?
could they grab? 	could I be grabbing?
could you be grabbing?
could he be grabbing?
could we be grabbing?
could you be grabbing?
could they be grabbing? 	could I have grabbed?
could you have grabbed?
could he have grabbed?
could we have grabbed?
could you have grabbed?
could they have grabbed? 	could I have been grabbing?
could you have been grabbing?
could he have been grabbing?
could we have been grabbing?
could you have been grabbing?
could they have been grabbing? 	

Interro-negative form 	
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couldn't I grab?
couldn't you grab?
couldn't he grab?
couldn't we grab?
couldn't you grab?
couldn't they grab? 	couldn't I be grabbing?
couldn't you be grabbing?
couldn't he be grabbing?
couldn't we be grabbing?
couldn't you be grabbing?
couldn't they be grabbing? 	couldn't I have grabbed?
couldn't you have grabbed?
couldn't he have grabbed?
couldn't we have grabbed?
couldn't you have grabbed?
couldn't they have grabbed? 	couldn't I have been grabbing?
couldn't you have been grabbing?
couldn't he have been grabbing?
couldn't we have been grabbing?
couldn't you have been grabbing?
couldn't they have been grabbing?