I could house-train you could house-train she could house-train we could house-train you could house-train they could house-train
V-ing form
I could be house-training you could be house-training she could be house-training we could be house-training you could be house-training they could be house-training
Perfect
I could have house-trained you could have house-trained she could have house-trained we could have house-trained you could have house-trained they could have house-trained
V-ing perfect
I could have been house-training you could have been house-training she could have been house-training we could have been house-training you could have been house-training they could have been house-training
Negation
Simple form
I couldn't house-train you couldn't house-train she couldn't house-train we couldn't house-train you couldn't house-train they couldn't house-train
V-ing form
I couldn't be house-training you couldn't be house-training she couldn't be house-training we couldn't be house-training you couldn't be house-training they couldn't be house-training
Perfect
I couldn't have house-trained you couldn't have house-trained she couldn't have house-trained we couldn't have house-trained you couldn't have house-trained they couldn't have house-trained
V-ing perfect
I couldn't have been house-training you couldn't have been house-training she couldn't have been house-training we couldn't have been house-training you couldn't have been house-training they couldn't have been house-training
Interrogative form
Simple form
could I house-train? could you house-train? could she house-train? could we house-train? could you house-train? could they house-train?
V-ing form
could I be house-training? could you be house-training? could she be house-training? could we be house-training? could you be house-training? could they be house-training?
Perfect
could I have house-trained? could you have house-trained? could she have house-trained? could we have house-trained? could you have house-trained? could they have house-trained?
V-ing perfect
could I have been house-training? could you have been house-training? could she have been house-training? could we have been house-training? could you have been house-training? could they have been house-training?
Interro-negative form
Simple form
couldn't I house-train? couldn't you house-train? couldn't she house-train? couldn't we house-train? couldn't you house-train? couldn't they house-train?
V-ing form
couldn't I be house-training? couldn't you be house-training? couldn't she be house-training? couldn't we be house-training? couldn't you be house-training? couldn't they be house-training?
Perfect
couldn't I have house-trained? couldn't you have house-trained? couldn't she have house-trained? couldn't we have house-trained? couldn't you have house-trained? couldn't they have house-trained?
V-ing perfect
couldn't I have been house-training? couldn't you have been house-training? couldn't she have been house-training? couldn't we have been house-training? couldn't you have been house-training? couldn't they have been house-training?