I could instruct you could instruct she could instruct we could instruct you could instruct they could instruct
V-ing form
I could be instructing you could be instructing she could be instructing we could be instructing you could be instructing they could be instructing
Perfect
I could have instructed you could have instructed she could have instructed we could have instructed you could have instructed they could have instructed
V-ing perfect
I could have been instructing you could have been instructing she could have been instructing we could have been instructing you could have been instructing they could have been instructing
Negation
Simple form
I couldn't instruct you couldn't instruct she couldn't instruct we couldn't instruct you couldn't instruct they couldn't instruct
V-ing form
I couldn't be instructing you couldn't be instructing she couldn't be instructing we couldn't be instructing you couldn't be instructing they couldn't be instructing
Perfect
I couldn't have instructed you couldn't have instructed she couldn't have instructed we couldn't have instructed you couldn't have instructed they couldn't have instructed
V-ing perfect
I couldn't have been instructing you couldn't have been instructing she couldn't have been instructing we couldn't have been instructing you couldn't have been instructing they couldn't have been instructing
Interrogative form
Simple form
could I instruct? could you instruct? could she instruct? could we instruct? could you instruct? could they instruct?
V-ing form
could I be instructing? could you be instructing? could she be instructing? could we be instructing? could you be instructing? could they be instructing?
Perfect
could I have instructed? could you have instructed? could she have instructed? could we have instructed? could you have instructed? could they have instructed?
V-ing perfect
could I have been instructing? could you have been instructing? could she have been instructing? could we have been instructing? could you have been instructing? could they have been instructing?
Interro-negative form
Simple form
couldn't I instruct? couldn't you instruct? couldn't she instruct? couldn't we instruct? couldn't you instruct? couldn't they instruct?
V-ing form
couldn't I be instructing? couldn't you be instructing? couldn't she be instructing? couldn't we be instructing? couldn't you be instructing? couldn't they be instructing?
Perfect
couldn't I have instructed? couldn't you have instructed? couldn't she have instructed? couldn't we have instructed? couldn't you have instructed? couldn't they have instructed?
V-ing perfect
couldn't I have been instructing? couldn't you have been instructing? couldn't she have been instructing? couldn't we have been instructing? couldn't you have been instructing? couldn't they have been instructing?