could hum
Regular verb: hum - humed- humed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could hum
you could hum
he could hum
we could hum
you could hum
they could hum 	I could be huming
you could be huming
he could be huming
we could be huming
you could be huming
they could be huming	I could have humed
you could have humed
he could have humed
we could have humed
you could have humed
they could have humed	I could have been huming
you could have been huming
he could have been huming
we could have been huming
you could have been huming
they could have been huming	

Negation 	
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I couldn't hum
you couldn't hum
he couldn't hum
we couldn't hum
you couldn't hum
they couldn't hum 	I couldn't be huming
you couldn't be huming
he couldn't be huming
we couldn't be huming
you couldn't be huming
they couldn't be huming	I couldn't have humed
you couldn't have humed
he couldn't have humed
we couldn't have humed
you couldn't have humed
they couldn't have humed	I couldn't have been huming
you couldn't have been huming
he couldn't have been huming
we couldn't have been huming
you couldn't have been huming
they couldn't have been huming	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I hum?
could you hum?
could he hum?
could we hum?
could you hum?
could they hum? 	could I be huming?
could you be huming?
could he be huming?
could we be huming?
could you be huming?
could they be huming? 	could I have humed?
could you have humed?
could he have humed?
could we have humed?
could you have humed?
could they have humed? 	could I have been huming?
could you have been huming?
could he have been huming?
could we have been huming?
could you have been huming?
could they have been huming? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I hum?
couldn't you hum?
couldn't he hum?
couldn't we hum?
couldn't you hum?
couldn't they hum? 	couldn't I be huming?
couldn't you be huming?
couldn't he be huming?
couldn't we be huming?
couldn't you be huming?
couldn't they be huming? 	couldn't I have humed?
couldn't you have humed?
couldn't he have humed?
couldn't we have humed?
couldn't you have humed?
couldn't they have humed? 	couldn't I have been huming?
couldn't you have been huming?
couldn't he have been huming?
couldn't we have been huming?
couldn't you have been huming?
couldn't they have been huming?