English verb conjugation
COULD UNDERLINE

Regular verb: underline - underlined - underlined

Affirmation

Simple form	V-ing form
I could underline you could underline he could underline we could underline you could underline they could underline	I could be underlining you could be underlining he could be underlining we could be underlining you could be underlining they could be underlining
Perfect	V-ing perfect
I could have underlined you could have underlined he could have underlined we could have underlined you could have underlined they could have underlined	I could have been underlining you could have been underlining he could have been underlining we could have been underlining you could have been underlining they could have been underlining

Negation

Simple form	V-ing form
I could not underline you could not underline he could not underline we could not underline you could not underline they could not underline	I could not be underlining you could not be underlining he could not be underlining we could not be underlining you could not be underlining they could not be underlining
Perfect	V-ing perfect
I could not have underlined you could not have underlined he could not have underlined we could not have underlined you could not have underlined they could not have underlined	I could not have been underlining you could not have been underlining he could not have been underlining we could not have been underlining you could not have been underlining they could not have been underlining

Interrogative form

Simple form	V-ing form
could I underline? could you underline? could he underline? could we underline? could you underline? could they underline?	could I be underlining? could you be underlining? could he be underlining? could we be underlining? could you be underlining? could they be underlining?
Perfect	V-ing perfect
could I have underlined? could you have underlined? could he have underlined? could we have underlined? could you have underlined? could they have underlined?	could I have been underlining? could you have been underlining? could he have been underlining? could we have been underlining? could you have been underlining? could they have been underlining?

Interro-negative form

Simple form	V-ing form
could I not underline? could you not underline? could he not underline? could we not underline? could you not underline? could they not underline?	could I not be underlining? could you not be underlining? could he not be underlining? could we not be underlining? could you not be underlining? could they not be underlining?
Perfect	V-ing perfect
could I not have underlined? could you not have underlined? could he not have underlined? could we not have underlined? could you not have underlined? could they not have underlined?	could I not have been underlining? could you not have been underlining? could he not have been underlining? could we not have been underlining? could you not have been underlining? could they not have been underlining?