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