English verb conjugation
CAN YACK

Regular verb: yack - yacked - yacked

Affirmation

Simple form	V-ing form
I can yack you can yack he can yack we can yack you can yack they can yack	I can be yacking you can be yacking he can be yacking we can be yacking you can be yacking they can be yacking
Perfect	V-ing perfect
I can have yacked you can have yacked he can have yacked we can have yacked you can have yacked they can have yacked	I can have been yacking you can have been yacking he can have been yacking we can have been yacking you can have been yacking they can have been yacking

Negation

Simple form	V-ing form
I can't yack you can't yack he can't yack we can't yack you can't yack they can't yack	I can't be yacking you can't be yacking he can't be yacking we can't be yacking you can't be yacking they can't be yacking
Perfect	V-ing perfect
I can't have yacked you can't have yacked he can't have yacked we can't have yacked you can't have yacked they can't have yacked	I can't have been yacking you can't have been yacking he can't have been yacking we can't have been yacking you can't have been yacking they can't have been yacking

Interrogative form

Simple form	V-ing form
can I yack? can you yack? can he yack? can we yack? can you yack? can they yack?	can I be yacking? can you be yacking? can he be yacking? can we be yacking? can you be yacking? can they be yacking?
Perfect	V-ing perfect
can I have yacked? can you have yacked? can he have yacked? can we have yacked? can you have yacked? can they have yacked?	can I have been yacking? can you have been yacking? can he have been yacking? can we have been yacking? can you have been yacking? can they have been yacking?

Interro-negative form

Simple form	V-ing form
can't I yack? can't you yack? can't he yack? can't we yack? can't you yack? can't they yack?	can't I be yacking? can't you be yacking? can't he be yacking? can't we be yacking? can't you be yacking? can't they be yacking?
Perfect	V-ing perfect
can't I have yacked? can't you have yacked? can't he have yacked? can't we have yacked? can't you have yacked? can't they have yacked?	can't I have been yacking? can't you have been yacking? can't he have been yacking? can't we have been yacking? can't you have been yacking? can't they have been yacking?