English verb conjugation
COULD CHECKMATE

Regular verb: checkmate - checkmated - checkmated

Affirmation

Simple form	V-ing form
I could checkmate you could checkmate he could checkmate we could checkmate you could checkmate they could checkmate	I could be checkmating you could be checkmating he could be checkmating we could be checkmating you could be checkmating they could be checkmating
Perfect	V-ing perfect
I could have checkmated you could have checkmated he could have checkmated we could have checkmated you could have checkmated they could have checkmated	I could have been checkmating you could have been checkmating he could have been checkmating we could have been checkmating you could have been checkmating they could have been checkmating

Negation

Simple form	V-ing form
I couldn't checkmate you couldn't checkmate he couldn't checkmate we couldn't checkmate you couldn't checkmate they couldn't checkmate	I couldn't be checkmating you couldn't be checkmating he couldn't be checkmating we couldn't be checkmating you couldn't be checkmating they couldn't be checkmating
Perfect	V-ing perfect
I couldn't have checkmated you couldn't have checkmated he couldn't have checkmated we couldn't have checkmated you couldn't have checkmated they couldn't have checkmated	I couldn't have been checkmating you couldn't have been checkmating he couldn't have been checkmating we couldn't have been checkmating you couldn't have been checkmating they couldn't have been checkmating

Interrogative form

Simple form	V-ing form
could I checkmate? could you checkmate? could he checkmate? could we checkmate? could you checkmate? could they checkmate?	could I be checkmating? could you be checkmating? could he be checkmating? could we be checkmating? could you be checkmating? could they be checkmating?
Perfect	V-ing perfect
could I have checkmated? could you have checkmated? could he have checkmated? could we have checkmated? could you have checkmated? could they have checkmated?	could I have been checkmating? could you have been checkmating? could he have been checkmating? could we have been checkmating? could you have been checkmating? could they have been checkmating?

Interro-negative form

Simple form	V-ing form
couldn't I checkmate? couldn't you checkmate? couldn't he checkmate? couldn't we checkmate? couldn't you checkmate? couldn't they checkmate?	couldn't I be checkmating? couldn't you be checkmating? couldn't he be checkmating? couldn't we be checkmating? couldn't you be checkmating? couldn't they be checkmating?
Perfect	V-ing perfect
couldn't I have checkmated? couldn't you have checkmated? couldn't he have checkmated? couldn't we have checkmated? couldn't you have checkmated? couldn't they have checkmated?	couldn't I have been checkmating? couldn't you have been checkmating? couldn't he have been checkmating? couldn't we have been checkmating? couldn't you have been checkmating? couldn't they have been checkmating?