could lack
Regular verb: lack - lacked- lacked

Affirmation 	
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I could lack
you could lack
he could lack
we could lack
you could lack
they could lack 	I could be lacking
you could be lacking
he could be lacking
we could be lacking
you could be lacking
they could be lacking	I could have lacked
you could have lacked
he could have lacked
we could have lacked
you could have lacked
they could have lacked	I could have been lacking
you could have been lacking
he could have been lacking
we could have been lacking
you could have been lacking
they could have been lacking	

Negation 	
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I couldn't lack
you couldn't lack
he couldn't lack
we couldn't lack
you couldn't lack
they couldn't lack 	I couldn't be lacking
you couldn't be lacking
he couldn't be lacking
we couldn't be lacking
you couldn't be lacking
they couldn't be lacking	I couldn't have lacked
you couldn't have lacked
he couldn't have lacked
we couldn't have lacked
you couldn't have lacked
they couldn't have lacked	I couldn't have been lacking
you couldn't have been lacking
he couldn't have been lacking
we couldn't have been lacking
you couldn't have been lacking
they couldn't have been lacking	

Interrogative form 	
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could I lack?
could you lack?
could he lack?
could we lack?
could you lack?
could they lack? 	could I be lacking?
could you be lacking?
could he be lacking?
could we be lacking?
could you be lacking?
could they be lacking? 	could I have lacked?
could you have lacked?
could he have lacked?
could we have lacked?
could you have lacked?
could they have lacked? 	could I have been lacking?
could you have been lacking?
could he have been lacking?
could we have been lacking?
could you have been lacking?
could they have been lacking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I lack?
couldn't you lack?
couldn't he lack?
couldn't we lack?
couldn't you lack?
couldn't they lack? 	couldn't I be lacking?
couldn't you be lacking?
couldn't he be lacking?
couldn't we be lacking?
couldn't you be lacking?
couldn't they be lacking? 	couldn't I have lacked?
couldn't you have lacked?
couldn't he have lacked?
couldn't we have lacked?
couldn't you have lacked?
couldn't they have lacked? 	couldn't I have been lacking?
couldn't you have been lacking?
couldn't he have been lacking?
couldn't we have been lacking?
couldn't you have been lacking?
couldn't they have been lacking?