I could trephine you could trephine she could trephine we could trephine you could trephine they could trephine
V-ing form
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
I could have trephined you could have trephined she could have trephined we could have trephined you could have trephined they could have trephined
V-ing perfect
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
I couldn't trephine you couldn't trephine she couldn't trephine we couldn't trephine you couldn't trephine they couldn't trephine
V-ing form
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
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
V-ing perfect
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
could I trephine? could you trephine? could she trephine? could we trephine? could you trephine? could they trephine?
V-ing form
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
could I have trephined? could you have trephined? could she have trephined? could we have trephined? could you have trephined? could they have trephined?
V-ing perfect
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
couldn't I trephine? couldn't you trephine? couldn't she trephine? couldn't we trephine? couldn't you trephine? couldn't they trephine?
V-ing form
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
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?
V-ing perfect
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?