I can alter you can alter she can alter we can alter you can alter they can alter
V-ing form
I can be altering you can be altering she can be altering we can be altering you can be altering they can be altering
Perfect
I can have altered you can have altered she can have altered we can have altered you can have altered they can have altered
V-ing perfect
I can have been altering you can have been altering she can have been altering we can have been altering you can have been altering they can have been altering
Negation
Simple form
I can't alter you can't alter she can't alter we can't alter you can't alter they can't alter
V-ing form
I can't be altering you can't be altering she can't be altering we can't be altering you can't be altering they can't be altering
Perfect
I can't have altered you can't have altered she can't have altered we can't have altered you can't have altered they can't have altered
V-ing perfect
I can't have been altering you can't have been altering she can't have been altering we can't have been altering you can't have been altering they can't have been altering
Interrogative form
Simple form
can I alter? can you alter? can she alter? can we alter? can you alter? can they alter?
V-ing form
can I be altering? can you be altering? can she be altering? can we be altering? can you be altering? can they be altering?
Perfect
can I have altered? can you have altered? can she have altered? can we have altered? can you have altered? can they have altered?
V-ing perfect
can I have been altering? can you have been altering? can she have been altering? can we have been altering? can you have been altering? can they have been altering?
Interro-negative form
Simple form
can't I alter? can't you alter? can't she alter? can't we alter? can't you alter? can't they alter?
V-ing form
can't I be altering? can't you be altering? can't she be altering? can't we be altering? can't you be altering? can't they be altering?
Perfect
can't I have altered? can't you have altered? can't she have altered? can't we have altered? can't you have altered? can't they have altered?
V-ing perfect
can't I have been altering? can't you have been altering? can't she have been altering? can't we have been altering? can't you have been altering? can't they have been altering?