English verb conjugation
CAN ALTER

Regular verb: alter - altered - altered

Affirmation

Simple form	V-ing form
I can alter you can alter he can alter we can alter you can alter they can alter	I can be altering you can be altering he can be altering we can be altering you can be altering they can be altering
Perfect	V-ing perfect
I can have altered you can have altered he can have altered we can have altered you can have altered they can have altered	I can have been altering you can have been altering he can have been altering we can have been altering you can have been altering they can have been altering

Negation

Simple form	V-ing form
I cannot alter you cannot alter he cannot alter we cannot alter you cannot alter they cannot alter	I cannot be altering you cannot be altering he cannot be altering we cannot be altering you cannot be altering they cannot be altering
Perfect	V-ing perfect
I cannot have altered you cannot have altered he cannot have altered we cannot have altered you cannot have altered they cannot have altered	I cannot have been altering you cannot have been altering he cannot have been altering we cannot have been altering you cannot have been altering they cannot have been altering

Interrogative form

Simple form	V-ing form
can I alter? can you alter? can he alter? can we alter? can you alter? can they alter?	can I be altering? can you be altering? can he be altering? can we be altering? can you be altering? can they be altering?
Perfect	V-ing perfect
can I have altered? can you have altered? can he have altered? can we have altered? can you have altered? can they have altered?	can I have been altering? can you have been altering? can he have been altering? can we have been altering? can you have been altering? can they have been altering?

Interro-negative form

Simple form	V-ing form
can I not alter? can you not alter? can he not alter? can we not alter? can you not alter? can they not alter?	can I not be altering? can you not be altering? can he not be altering? can we not be altering? can you not be altering? can they not be altering?
Perfect	V-ing perfect
can I not have altered? can you not have altered? can he not have altered? can we not have altered? can you not have altered? can they not have altered?	can I not have been altering? can you not have been altering? can he not have been altering? can we not have been altering? can you not have been altering? can they not have been altering?