English verb conjugation
CAN TESTIFY

Regular verb: testify - testified - testified

Affirmation

Simple form	V-ing form
I can testify you can testify he can testify we can testify you can testify they can testify	I can be testifying you can be testifying he can be testifying we can be testifying you can be testifying they can be testifying
Perfect	V-ing perfect
I can have testified you can have testified he can have testified we can have testified you can have testified they can have testified	I can have been testifying you can have been testifying he can have been testifying we can have been testifying you can have been testifying they can have been testifying

Negation

Simple form	V-ing form
I can't testify you can't testify he can't testify we can't testify you can't testify they can't testify	I can't be testifying you can't be testifying he can't be testifying we can't be testifying you can't be testifying they can't be testifying
Perfect	V-ing perfect
I can't have testified you can't have testified he can't have testified we can't have testified you can't have testified they can't have testified	I can't have been testifying you can't have been testifying he can't have been testifying we can't have been testifying you can't have been testifying they can't have been testifying

Interrogative form

Simple form	V-ing form
can I testify? can you testify? can he testify? can we testify? can you testify? can they testify?	can I be testifying? can you be testifying? can he be testifying? can we be testifying? can you be testifying? can they be testifying?
Perfect	V-ing perfect
can I have testified? can you have testified? can he have testified? can we have testified? can you have testified? can they have testified?	can I have been testifying? can you have been testifying? can he have been testifying? can we have been testifying? can you have been testifying? can they have been testifying?

Interro-negative form

Simple form	V-ing form
can't I testify? can't you testify? can't he testify? can't we testify? can't you testify? can't they testify?	can't I be testifying? can't you be testifying? can't he be testifying? can't we be testifying? can't you be testifying? can't they be testifying?
Perfect	V-ing perfect
can't I have testified? can't you have testified? can't he have testified? can't we have testified? can't you have testified? can't they have testified?	can't I have been testifying? can't you have been testifying? can't he have been testifying? can't we have been testifying? can't you have been testifying? can't they have been testifying?