English verb conjugation
COULD TUMBLE

Regular verb: tumble - tumbled - tumbled

Affirmation

Simple form	V-ing form
I could tumble you could tumble he could tumble we could tumble you could tumble they could tumble	I could be tumbling you could be tumbling he could be tumbling we could be tumbling you could be tumbling they could be tumbling
Perfect	V-ing perfect
I could have tumbled you could have tumbled he could have tumbled we could have tumbled you could have tumbled they could have tumbled	I could have been tumbling you could have been tumbling he could have been tumbling we could have been tumbling you could have been tumbling they could have been tumbling

Negation

Simple form	V-ing form
I couldn't tumble you couldn't tumble he couldn't tumble we couldn't tumble you couldn't tumble they couldn't tumble	I couldn't be tumbling you couldn't be tumbling he couldn't be tumbling we couldn't be tumbling you couldn't be tumbling they couldn't be tumbling
Perfect	V-ing perfect
I couldn't have tumbled you couldn't have tumbled he couldn't have tumbled we couldn't have tumbled you couldn't have tumbled they couldn't have tumbled	I couldn't have been tumbling you couldn't have been tumbling he couldn't have been tumbling we couldn't have been tumbling you couldn't have been tumbling they couldn't have been tumbling

Interrogative form

Simple form	V-ing form
could I tumble? could you tumble? could he tumble? could we tumble? could you tumble? could they tumble?	could I be tumbling? could you be tumbling? could he be tumbling? could we be tumbling? could you be tumbling? could they be tumbling?
Perfect	V-ing perfect
could I have tumbled? could you have tumbled? could he have tumbled? could we have tumbled? could you have tumbled? could they have tumbled?	could I have been tumbling? could you have been tumbling? could he have been tumbling? could we have been tumbling? could you have been tumbling? could they have been tumbling?

Interro-negative form

Simple form	V-ing form
couldn't I tumble? couldn't you tumble? couldn't he tumble? couldn't we tumble? couldn't you tumble? couldn't they tumble?	couldn't I be tumbling? couldn't you be tumbling? couldn't he be tumbling? couldn't we be tumbling? couldn't you be tumbling? couldn't they be tumbling?
Perfect	V-ing perfect
couldn't I have tumbled? couldn't you have tumbled? couldn't he have tumbled? couldn't we have tumbled? couldn't you have tumbled? couldn't they have tumbled?	couldn't I have been tumbling? couldn't you have been tumbling? couldn't he have been tumbling? couldn't we have been tumbling? couldn't you have been tumbling? couldn't they have been tumbling?