English verb conjugation
COULD TREPHINE

Regular verb: trephine - trephined - trephined

Affirmation

Simple form	V-ing form
I could trephine you could trephine she could trephine we could trephine you could trephine they could trephine	I could be trephining you could be trephining she could be trephining we could be trephining you could be trephining they could be trephining
Perfect	V-ing perfect
I could have trephined you could have trephined she could have trephined we could have trephined you could have trephined they could have trephined	I could have been trephining you could have been trephining she could have been trephining we could have been trephining you could have been trephining they could have been trephining

Negation

Simple form	V-ing form
I couldn't trephine you couldn't trephine she couldn't trephine we couldn't trephine you couldn't trephine they couldn't trephine	I couldn't be trephining you couldn't be trephining she couldn't be trephining we couldn't be trephining you couldn't be trephining they couldn't be trephining
Perfect	V-ing perfect
I couldn't have trephined you couldn't have trephined she couldn't have trephined we couldn't have trephined you couldn't have trephined they couldn't have trephined	I couldn't have been trephining you couldn't have been trephining she couldn't have been trephining we couldn't have been trephining you couldn't have been trephining they couldn't have been trephining

Interrogative form

Simple form	V-ing form
could I trephine? could you trephine? could she trephine? could we trephine? could you trephine? could they trephine?	could I be trephining? could you be trephining? could she be trephining? could we be trephining? could you be trephining? could they be trephining?
Perfect	V-ing perfect
could I have trephined? could you have trephined? could she have trephined? could we have trephined? could you have trephined? could they have trephined?	could I have been trephining? could you have been trephining? could she have been trephining? could we have been trephining? could you have been trephining? could they have been trephining?

Interro-negative form

Simple form	V-ing form
couldn't I trephine? couldn't you trephine? couldn't she trephine? couldn't we trephine? couldn't you trephine? couldn't they trephine?	couldn't I be trephining? couldn't you be trephining? couldn't she be trephining? couldn't we be trephining? couldn't you be trephining? couldn't they be trephining?
Perfect	V-ing perfect
couldn't I have trephined? couldn't you have trephined? couldn't she have trephined? couldn't we have trephined? couldn't you have trephined? couldn't they have trephined?	couldn't I have been trephining? couldn't you have been trephining? couldn't she have been trephining? couldn't we have been trephining? couldn't you have been trephining? couldn't they have been trephining?