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