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