can mumble
Regular verb: mumble - mumbled- mumbled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can mumble
you can mumble
he can mumble
we can mumble
you can mumble
they can mumble 	I can be mumbling
you can be mumbling
he can be mumbling
we can be mumbling
you can be mumbling
they can be mumbling	I can have mumbled
you can have mumbled
he can have mumbled
we can have mumbled
you can have mumbled
they can have mumbled	I can have been mumbling
you can have been mumbling
he can have been mumbling
we can have been mumbling
you can have been mumbling
they can have been mumbling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can't mumble
you can't mumble
he can't mumble
we can't mumble
you can't mumble
they can't mumble 	I can't be mumbling
you can't be mumbling
he can't be mumbling
we can't be mumbling
you can't be mumbling
they can't be mumbling	I can't have mumbled
you can't have mumbled
he can't have mumbled
we can't have mumbled
you can't have mumbled
they can't have mumbled	I can't have been mumbling
you can't have been mumbling
he can't have been mumbling
we can't have been mumbling
you can't have been mumbling
they can't have been mumbling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I mumble?
can you mumble?
can he mumble?
can we mumble?
can you mumble?
can they mumble? 	can I be mumbling?
can you be mumbling?
can he be mumbling?
can we be mumbling?
can you be mumbling?
can they be mumbling? 	can I have mumbled?
can you have mumbled?
can he have mumbled?
can we have mumbled?
can you have mumbled?
can they have mumbled? 	can I have been mumbling?
can you have been mumbling?
can he have been mumbling?
can we have been mumbling?
can you have been mumbling?
can they have been mumbling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can't I mumble?
can't you mumble?
can't he mumble?
can't we mumble?
can't you mumble?
can't they mumble? 	can't I be mumbling?
can't you be mumbling?
can't he be mumbling?
can't we be mumbling?
can't you be mumbling?
can't they be mumbling? 	can't I have mumbled?
can't you have mumbled?
can't he have mumbled?
can't we have mumbled?
can't you have mumbled?
can't they have mumbled? 	can't I have been mumbling?
can't you have been mumbling?
can't he have been mumbling?
can't we have been mumbling?
can't you have been mumbling?
can't they have been mumbling?