I can omit you can omit he can omit we can omit you can omit they can omit
V-ing form
I can be omitting you can be omitting he can be omitting we can be omitting you can be omitting they can be omitting
Perfect
I can have omitted you can have omitted he can have omitted we can have omitted you can have omitted they can have omitted
V-ing perfect
I can have been omitting you can have been omitting he can have been omitting we can have been omitting you can have been omitting they can have been omitting
Negation
Simple form
I cannot omit you cannot omit he cannot omit we cannot omit you cannot omit they cannot omit
V-ing form
I cannot be omitting you cannot be omitting he cannot be omitting we cannot be omitting you cannot be omitting they cannot be omitting
Perfect
I cannot have omitted you cannot have omitted he cannot have omitted we cannot have omitted you cannot have omitted they cannot have omitted
V-ing perfect
I cannot have been omitting you cannot have been omitting he cannot have been omitting we cannot have been omitting you cannot have been omitting they cannot have been omitting
Interrogative form
Simple form
can I omit? can you omit? can he omit? can we omit? can you omit? can they omit?
V-ing form
can I be omitting? can you be omitting? can he be omitting? can we be omitting? can you be omitting? can they be omitting?
Perfect
can I have omitted? can you have omitted? can he have omitted? can we have omitted? can you have omitted? can they have omitted?
V-ing perfect
can I have been omitting? can you have been omitting? can he have been omitting? can we have been omitting? can you have been omitting? can they have been omitting?
Interro-negative form
Simple form
can I not omit? can you not omit? can he not omit? can we not omit? can you not omit? can they not omit?
V-ing form
can I not be omitting? can you not be omitting? can he not be omitting? can we not be omitting? can you not be omitting? can they not be omitting?
Perfect
can I not have omitted? can you not have omitted? can he not have omitted? can we not have omitted? can you not have omitted? can they not have omitted?
V-ing perfect
can I not have been omitting? can you not have been omitting? can he not have been omitting? can we not have been omitting? can you not have been omitting? can they not have been omitting?