English verb conjugation
COULD THINK

Irregular verb: think - thought - thought

Affirmation

Simple form	V-ing form
I could think you could think he could think we could think you could think they could think	I could be thinking you could be thinking he could be thinking we could be thinking you could be thinking they could be thinking
Perfect	V-ing perfect
I could have thought you could have thought he could have thought we could have thought you could have thought they could have thought	I could have been thinking you could have been thinking he could have been thinking we could have been thinking you could have been thinking they could have been thinking

Negation

Simple form	V-ing form
I couldn't think you couldn't think he couldn't think we couldn't think you couldn't think they couldn't think	I couldn't be thinking you couldn't be thinking he couldn't be thinking we couldn't be thinking you couldn't be thinking they couldn't be thinking
Perfect	V-ing perfect
I couldn't have thought you couldn't have thought he couldn't have thought we couldn't have thought you couldn't have thought they couldn't have thought	I couldn't have been thinking you couldn't have been thinking he couldn't have been thinking we couldn't have been thinking you couldn't have been thinking they couldn't have been thinking

Interrogative form

Simple form	V-ing form
could I think? could you think? could he think? could we think? could you think? could they think?	could I be thinking? could you be thinking? could he be thinking? could we be thinking? could you be thinking? could they be thinking?
Perfect	V-ing perfect
could I have thought? could you have thought? could he have thought? could we have thought? could you have thought? could they have thought?	could I have been thinking? could you have been thinking? could he have been thinking? could we have been thinking? could you have been thinking? could they have been thinking?

Interro-negative form

Simple form	V-ing form
couldn't I think? couldn't you think? couldn't he think? couldn't we think? couldn't you think? couldn't they think?	couldn't I be thinking? couldn't you be thinking? couldn't he be thinking? couldn't we be thinking? couldn't you be thinking? couldn't they be thinking?
Perfect	V-ing perfect
couldn't I have thought? couldn't you have thought? couldn't he have thought? couldn't we have thought? couldn't you have thought? couldn't they have thought?	couldn't I have been thinking? couldn't you have been thinking? couldn't he have been thinking? couldn't we have been thinking? couldn't you have been thinking? couldn't they have been thinking?