I could machine you could machine she could machine we could machine you could machine they could machine
V-ing form
I could be machining you could be machining she could be machining we could be machining you could be machining they could be machining
Perfect
I could have machined you could have machined she could have machined we could have machined you could have machined they could have machined
V-ing perfect
I could have been machining you could have been machining she could have been machining we could have been machining you could have been machining they could have been machining
Negation
Simple form
I could not machine you could not machine she could not machine we could not machine you could not machine they could not machine
V-ing form
I could not be machining you could not be machining she could not be machining we could not be machining you could not be machining they could not be machining
Perfect
I could not have machined you could not have machined she could not have machined we could not have machined you could not have machined they could not have machined
V-ing perfect
I could not have been machining you could not have been machining she could not have been machining we could not have been machining you could not have been machining they could not have been machining
Interrogative form
Simple form
could I machine? could you machine? could she machine? could we machine? could you machine? could they machine?
V-ing form
could I be machining? could you be machining? could she be machining? could we be machining? could you be machining? could they be machining?
Perfect
could I have machined? could you have machined? could she have machined? could we have machined? could you have machined? could they have machined?
V-ing perfect
could I have been machining? could you have been machining? could she have been machining? could we have been machining? could you have been machining? could they have been machining?
Interro-negative form
Simple form
could I not machine? could you not machine? could she not machine? could we not machine? could you not machine? could they not machine?
V-ing form
could I not be machining? could you not be machining? could she not be machining? could we not be machining? could you not be machining? could they not be machining?
Perfect
could I not have machined? could you not have machined? could she not have machined? could we not have machined? could you not have machined? could they not have machined?
V-ing perfect
could I not have been machining? could you not have been machining? could she not have been machining? could we not have been machining? could you not have been machining? could they not have been machining?