English verb conjugation
COULD WHISTLE

Regular verb: whistle - whistled - whistled

Affirmation

Simple form	V-ing form
I could whistle you could whistle he could whistle we could whistle you could whistle they could whistle	I could be whistling you could be whistling he could be whistling we could be whistling you could be whistling they could be whistling
Perfect	V-ing perfect
I could have whistled you could have whistled he could have whistled we could have whistled you could have whistled they could have whistled	I could have been whistling you could have been whistling he could have been whistling we could have been whistling you could have been whistling they could have been whistling

Negation

Simple form	V-ing form
I couldn't whistle you couldn't whistle he couldn't whistle we couldn't whistle you couldn't whistle they couldn't whistle	I couldn't be whistling you couldn't be whistling he couldn't be whistling we couldn't be whistling you couldn't be whistling they couldn't be whistling
Perfect	V-ing perfect
I couldn't have whistled you couldn't have whistled he couldn't have whistled we couldn't have whistled you couldn't have whistled they couldn't have whistled	I couldn't have been whistling you couldn't have been whistling he couldn't have been whistling we couldn't have been whistling you couldn't have been whistling they couldn't have been whistling

Interrogative form

Simple form	V-ing form
could I whistle? could you whistle? could he whistle? could we whistle? could you whistle? could they whistle?	could I be whistling? could you be whistling? could he be whistling? could we be whistling? could you be whistling? could they be whistling?
Perfect	V-ing perfect
could I have whistled? could you have whistled? could he have whistled? could we have whistled? could you have whistled? could they have whistled?	could I have been whistling? could you have been whistling? could he have been whistling? could we have been whistling? could you have been whistling? could they have been whistling?

Interro-negative form

Simple form	V-ing form
couldn't I whistle? couldn't you whistle? couldn't he whistle? couldn't we whistle? couldn't you whistle? couldn't they whistle?	couldn't I be whistling? couldn't you be whistling? couldn't he be whistling? couldn't we be whistling? couldn't you be whistling? couldn't they be whistling?
Perfect	V-ing perfect
couldn't I have whistled? couldn't you have whistled? couldn't he have whistled? couldn't we have whistled? couldn't you have whistled? couldn't they have whistled?	couldn't I have been whistling? couldn't you have been whistling? couldn't he have been whistling? couldn't we have been whistling? couldn't you have been whistling? couldn't they have been whistling?