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