English verb conjugation
COULD MUTTER

Regular verb: mutter - muttered - muttered

Affirmation

Simple form	V-ing form
I could mutter you could mutter he could mutter we could mutter you could mutter they could mutter	I could be muttering you could be muttering he could be muttering we could be muttering you could be muttering they could be muttering
Perfect	V-ing perfect
I could have muttered you could have muttered he could have muttered we could have muttered you could have muttered they could have muttered	I could have been muttering you could have been muttering he could have been muttering we could have been muttering you could have been muttering they could have been muttering

Negation

Simple form	V-ing form
I couldn't mutter you couldn't mutter he couldn't mutter we couldn't mutter you couldn't mutter they couldn't mutter	I couldn't be muttering you couldn't be muttering he couldn't be muttering we couldn't be muttering you couldn't be muttering they couldn't be muttering
Perfect	V-ing perfect
I couldn't have muttered you couldn't have muttered he couldn't have muttered we couldn't have muttered you couldn't have muttered they couldn't have muttered	I couldn't have been muttering you couldn't have been muttering he couldn't have been muttering we couldn't have been muttering you couldn't have been muttering they couldn't have been muttering

Interrogative form

Simple form	V-ing form
could I mutter? could you mutter? could he mutter? could we mutter? could you mutter? could they mutter?	could I be muttering? could you be muttering? could he be muttering? could we be muttering? could you be muttering? could they be muttering?
Perfect	V-ing perfect
could I have muttered? could you have muttered? could he have muttered? could we have muttered? could you have muttered? could they have muttered?	could I have been muttering? could you have been muttering? could he have been muttering? could we have been muttering? could you have been muttering? could they have been muttering?

Interro-negative form

Simple form	V-ing form
couldn't I mutter? couldn't you mutter? couldn't he mutter? couldn't we mutter? couldn't you mutter? couldn't they mutter?	couldn't I be muttering? couldn't you be muttering? couldn't he be muttering? couldn't we be muttering? couldn't you be muttering? couldn't they be muttering?
Perfect	V-ing perfect
couldn't I have muttered? couldn't you have muttered? couldn't he have muttered? couldn't we have muttered? couldn't you have muttered? couldn't they have muttered?	couldn't I have been muttering? couldn't you have been muttering? couldn't he have been muttering? couldn't we have been muttering? couldn't you have been muttering? couldn't they have been muttering?