English verb conjugation
CAN LACK

Regular verb: lack - lacked - lacked

Affirmation

Simple form	V-ing form
I can lack you can lack he can lack we can lack you can lack they can lack	I can be lacking you can be lacking he can be lacking we can be lacking you can be lacking they can be lacking
Perfect	V-ing perfect
I can have lacked you can have lacked he can have lacked we can have lacked you can have lacked they can have lacked	I can have been lacking you can have been lacking he can have been lacking we can have been lacking you can have been lacking they can have been lacking

Negation

Simple form	V-ing form
I cannot lack you cannot lack he cannot lack we cannot lack you cannot lack they cannot lack	I cannot be lacking you cannot be lacking he cannot be lacking we cannot be lacking you cannot be lacking they cannot be lacking
Perfect	V-ing perfect
I cannot have lacked you cannot have lacked he cannot have lacked we cannot have lacked you cannot have lacked they cannot have lacked	I cannot have been lacking you cannot have been lacking he cannot have been lacking we cannot have been lacking you cannot have been lacking they cannot have been lacking

Interrogative form

Simple form	V-ing form
can I lack? can you lack? can he lack? can we lack? can you lack? can they lack?	can I be lacking? can you be lacking? can he be lacking? can we be lacking? can you be lacking? can they be lacking?
Perfect	V-ing perfect
can I have lacked? can you have lacked? can he have lacked? can we have lacked? can you have lacked? can they have lacked?	can I have been lacking? can you have been lacking? can he have been lacking? can we have been lacking? can you have been lacking? can they have been lacking?

Interro-negative form

Simple form	V-ing form
can I not lack? can you not lack? can he not lack? can we not lack? can you not lack? can they not lack?	can I not be lacking? can you not be lacking? can he not be lacking? can we not be lacking? can you not be lacking? can they not be lacking?
Perfect	V-ing perfect
can I not have lacked? can you not have lacked? can he not have lacked? can we not have lacked? can you not have lacked? can they not have lacked?	can I not have been lacking? can you not have been lacking? can he not have been lacking? can we not have been lacking? can you not have been lacking? can they not have been lacking?