I could commence you could commence she could commence we could commence you could commence they could commence
V-ing form
I could be commencing you could be commencing she could be commencing we could be commencing you could be commencing they could be commencing
Perfect
I could have commenced you could have commenced she 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 she 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 she 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 she 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 she 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 she 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 she commence? could we commence? could you commence? could they commence?
V-ing form
could I be commencing? could you be commencing? could she be commencing? could we be commencing? could you be commencing? could they be commencing?
Perfect
could I have commenced? could you have commenced? could she 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 she 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 she 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 she 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 she 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 she have been commencing? couldn't we have been commencing? couldn't you have been commencing? couldn't they have been commencing?