English verb conjugation
COULD COMBUST

Regular verb: combust - combusted - combusted

Affirmation

Simple form	V-ing form
I could combust you could combust he could combust we could combust you could combust they could combust	I could be combusting you could be combusting he could be combusting we could be combusting you could be combusting they could be combusting
Perfect	V-ing perfect
I could have combusted you could have combusted he could have combusted we could have combusted you could have combusted they could have combusted	I could have been combusting you could have been combusting he could have been combusting we could have been combusting you could have been combusting they could have been combusting

Negation

Simple form	V-ing form
I couldn't combust you couldn't combust he couldn't combust we couldn't combust you couldn't combust they couldn't combust	I couldn't be combusting you couldn't be combusting he couldn't be combusting we couldn't be combusting you couldn't be combusting they couldn't be combusting
Perfect	V-ing perfect
I couldn't have combusted you couldn't have combusted he couldn't have combusted we couldn't have combusted you couldn't have combusted they couldn't have combusted	I couldn't have been combusting you couldn't have been combusting he couldn't have been combusting we couldn't have been combusting you couldn't have been combusting they couldn't have been combusting

Interrogative form

Simple form	V-ing form
could I combust? could you combust? could he combust? could we combust? could you combust? could they combust?	could I be combusting? could you be combusting? could he be combusting? could we be combusting? could you be combusting? could they be combusting?
Perfect	V-ing perfect
could I have combusted? could you have combusted? could he have combusted? could we have combusted? could you have combusted? could they have combusted?	could I have been combusting? could you have been combusting? could he have been combusting? could we have been combusting? could you have been combusting? could they have been combusting?

Interro-negative form

Simple form	V-ing form
couldn't I combust? couldn't you combust? couldn't he combust? couldn't we combust? couldn't you combust? couldn't they combust?	couldn't I be combusting? couldn't you be combusting? couldn't he be combusting? couldn't we be combusting? couldn't you be combusting? couldn't they be combusting?
Perfect	V-ing perfect
couldn't I have combusted? couldn't you have combusted? couldn't he have combusted? couldn't we have combusted? couldn't you have combusted? couldn't they have combusted?	couldn't I have been combusting? couldn't you have been combusting? couldn't he have been combusting? couldn't we have been combusting? couldn't you have been combusting? couldn't they have been combusting?