I could train you could train he could train we could train you could train they could train
V-ing form
I could be training you could be training he could be training we could be training you could be training they could be training
Perfect
I could have trained you could have trained he could have trained we could have trained you could have trained they could have trained
V-ing perfect
I could have been training you could have been training he could have been training we could have been training you could have been training they could have been training
Negation
Simple form
I could not train you could not train he could not train we could not train you could not train they could not train
V-ing form
I could not be training you could not be training he could not be training we could not be training you could not be training they could not be training
Perfect
I could not have trained you could not have trained he could not have trained we could not have trained you could not have trained they could not have trained
V-ing perfect
I could not have been training you could not have been training he could not have been training we could not have been training you could not have been training they could not have been training
Interrogative form
Simple form
could I train? could you train? could he train? could we train? could you train? could they train?
V-ing form
could I be training? could you be training? could he be training? could we be training? could you be training? could they be training?
Perfect
could I have trained? could you have trained? could he have trained? could we have trained? could you have trained? could they have trained?
V-ing perfect
could I have been training? could you have been training? could he have been training? could we have been training? could you have been training? could they have been training?
Interro-negative form
Simple form
could I not train? could you not train? could he not train? could we not train? could you not train? could they not train?
V-ing form
could I not be training? could you not be training? could he not be training? could we not be training? could you not be training? could they not be training?
Perfect
could I not have trained? could you not have trained? could he not have trained? could we not have trained? could you not have trained? could they not have trained?
V-ing perfect
could I not have been training? could you not have been training? could he not have been training? could we not have been training? could you not have been training? could they not have been training?