I could inject you could inject he could inject we could inject you could inject they could inject
V-ing form
I could be injecting you could be injecting he could be injecting we could be injecting you could be injecting they could be injecting
Perfect
I could have injected you could have injected he could have injected we could have injected you could have injected they could have injected
V-ing perfect
I could have been injecting you could have been injecting he could have been injecting we could have been injecting you could have been injecting they could have been injecting
Negation
Simple form
I couldn't inject you couldn't inject he couldn't inject we couldn't inject you couldn't inject they couldn't inject
V-ing form
I couldn't be injecting you couldn't be injecting he couldn't be injecting we couldn't be injecting you couldn't be injecting they couldn't be injecting
Perfect
I couldn't have injected you couldn't have injected he couldn't have injected we couldn't have injected you couldn't have injected they couldn't have injected
V-ing perfect
I couldn't have been injecting you couldn't have been injecting he couldn't have been injecting we couldn't have been injecting you couldn't have been injecting they couldn't have been injecting
Interrogative form
Simple form
could I inject? could you inject? could he inject? could we inject? could you inject? could they inject?
V-ing form
could I be injecting? could you be injecting? could he be injecting? could we be injecting? could you be injecting? could they be injecting?
Perfect
could I have injected? could you have injected? could he have injected? could we have injected? could you have injected? could they have injected?
V-ing perfect
could I have been injecting? could you have been injecting? could he have been injecting? could we have been injecting? could you have been injecting? could they have been injecting?
Interro-negative form
Simple form
couldn't I inject? couldn't you inject? couldn't he inject? couldn't we inject? couldn't you inject? couldn't they inject?
V-ing form
couldn't I be injecting? couldn't you be injecting? couldn't he be injecting? couldn't we be injecting? couldn't you be injecting? couldn't they be injecting?
Perfect
couldn't I have injected? couldn't you have injected? couldn't he have injected? couldn't we have injected? couldn't you have injected? couldn't they have injected?
V-ing perfect
couldn't I have been injecting? couldn't you have been injecting? couldn't he have been injecting? couldn't we have been injecting? couldn't you have been injecting? couldn't they have been injecting?