I could float you could float he could float we could float you could float they could float
V-ing form
I could be floating you could be floating he could be floating we could be floating you could be floating they could be floating
Perfect
I could have floated you could have floated he could have floated we could have floated you could have floated they could have floated
V-ing perfect
I could have been floating you could have been floating he could have been floating we could have been floating you could have been floating they could have been floating
Negation
Simple form
I couldn't float you couldn't float he couldn't float we couldn't float you couldn't float they couldn't float
V-ing form
I couldn't be floating you couldn't be floating he couldn't be floating we couldn't be floating you couldn't be floating they couldn't be floating
Perfect
I couldn't have floated you couldn't have floated he couldn't have floated we couldn't have floated you couldn't have floated they couldn't have floated
V-ing perfect
I couldn't have been floating you couldn't have been floating he couldn't have been floating we couldn't have been floating you couldn't have been floating they couldn't have been floating
Interrogative form
Simple form
could I float? could you float? could he float? could we float? could you float? could they float?
V-ing form
could I be floating? could you be floating? could he be floating? could we be floating? could you be floating? could they be floating?
Perfect
could I have floated? could you have floated? could he have floated? could we have floated? could you have floated? could they have floated?
V-ing perfect
could I have been floating? could you have been floating? could he have been floating? could we have been floating? could you have been floating? could they have been floating?
Interro-negative form
Simple form
couldn't I float? couldn't you float? couldn't he float? couldn't we float? couldn't you float? couldn't they float?
V-ing form
couldn't I be floating? couldn't you be floating? couldn't he be floating? couldn't we be floating? couldn't you be floating? couldn't they be floating?
Perfect
couldn't I have floated? couldn't you have floated? couldn't he have floated? couldn't we have floated? couldn't you have floated? couldn't they have floated?
V-ing perfect
couldn't I have been floating? couldn't you have been floating? couldn't he have been floating? couldn't we have been floating? couldn't you have been floating? couldn't they have been floating?