could sob
Regular verb: sob - sobbed- sobbed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could sob
you could sob
he could sob
we could sob
you could sob
they could sob 	I could be sobbing
you could be sobbing
he could be sobbing
we could be sobbing
you could be sobbing
they could be sobbing	I could have sobbed
you could have sobbed
he could have sobbed
we could have sobbed
you could have sobbed
they could have sobbed	I could have been sobbing
you could have been sobbing
he could have been sobbing
we could have been sobbing
you could have been sobbing
they could have been sobbing	

Negation 	
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I couldn't sob
you couldn't sob
he couldn't sob
we couldn't sob
you couldn't sob
they couldn't sob 	I couldn't be sobbing
you couldn't be sobbing
he couldn't be sobbing
we couldn't be sobbing
you couldn't be sobbing
they couldn't be sobbing	I couldn't have sobbed
you couldn't have sobbed
he couldn't have sobbed
we couldn't have sobbed
you couldn't have sobbed
they couldn't have sobbed	I couldn't have been sobbing
you couldn't have been sobbing
he couldn't have been sobbing
we couldn't have been sobbing
you couldn't have been sobbing
they couldn't have been sobbing	

Interrogative form 	
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could I sob?
could you sob?
could he sob?
could we sob?
could you sob?
could they sob? 	could I be sobbing?
could you be sobbing?
could he be sobbing?
could we be sobbing?
could you be sobbing?
could they be sobbing? 	could I have sobbed?
could you have sobbed?
could he have sobbed?
could we have sobbed?
could you have sobbed?
could they have sobbed? 	could I have been sobbing?
could you have been sobbing?
could he have been sobbing?
could we have been sobbing?
could you have been sobbing?
could they have been sobbing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I sob?
couldn't you sob?
couldn't he sob?
couldn't we sob?
couldn't you sob?
couldn't they sob? 	couldn't I be sobbing?
couldn't you be sobbing?
couldn't he be sobbing?
couldn't we be sobbing?
couldn't you be sobbing?
couldn't they be sobbing? 	couldn't I have sobbed?
couldn't you have sobbed?
couldn't he have sobbed?
couldn't we have sobbed?
couldn't you have sobbed?
couldn't they have sobbed? 	couldn't I have been sobbing?
couldn't you have been sobbing?
couldn't he have been sobbing?
couldn't we have been sobbing?
couldn't you have been sobbing?
couldn't they have been sobbing?