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