English verb conjugation
COULD GRAPH

Regular verb: graph - graphed - graphed

Affirmation

Simple form	V-ing form
I could graph you could graph he could graph we could graph you could graph they could graph	I could be graphing you could be graphing he could be graphing we could be graphing you could be graphing they could be graphing
Perfect	V-ing perfect
I could have graphed you could have graphed he could have graphed we could have graphed you could have graphed they could have graphed	I could have been graphing you could have been graphing he could have been graphing we could have been graphing you could have been graphing they could have been graphing

Negation

Simple form	V-ing form
I couldn't graph you couldn't graph he couldn't graph we couldn't graph you couldn't graph they couldn't graph	I couldn't be graphing you couldn't be graphing he couldn't be graphing we couldn't be graphing you couldn't be graphing they couldn't be graphing
Perfect	V-ing perfect
I couldn't have graphed you couldn't have graphed he couldn't have graphed we couldn't have graphed you couldn't have graphed they couldn't have graphed	I couldn't have been graphing you couldn't have been graphing he couldn't have been graphing we couldn't have been graphing you couldn't have been graphing they couldn't have been graphing

Interrogative form

Simple form	V-ing form
could I graph? could you graph? could he graph? could we graph? could you graph? could they graph?	could I be graphing? could you be graphing? could he be graphing? could we be graphing? could you be graphing? could they be graphing?
Perfect	V-ing perfect
could I have graphed? could you have graphed? could he have graphed? could we have graphed? could you have graphed? could they have graphed?	could I have been graphing? could you have been graphing? could he have been graphing? could we have been graphing? could you have been graphing? could they have been graphing?

Interro-negative form

Simple form	V-ing form
couldn't I graph? couldn't you graph? couldn't he graph? couldn't we graph? couldn't you graph? couldn't they graph?	couldn't I be graphing? couldn't you be graphing? couldn't he be graphing? couldn't we be graphing? couldn't you be graphing? couldn't they be graphing?
Perfect	V-ing perfect
couldn't I have graphed? couldn't you have graphed? couldn't he have graphed? couldn't we have graphed? couldn't you have graphed? couldn't they have graphed?	couldn't I have been graphing? couldn't you have been graphing? couldn't he have been graphing? couldn't we have been graphing? couldn't you have been graphing? couldn't they have been graphing?