could grade
Regular verb: grade - graded- graded

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could grade
you could grade
she could grade
we could grade
you could grade
they could grade 	I could be grading
you could be grading
she could be grading
we could be grading
you could be grading
they could be grading	I could have graded
you could have graded
she could have graded
we could have graded
you could have graded
they could have graded	I could have been grading
you could have been grading
she could have been grading
we could have been grading
you could have been grading
they could have been grading	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not grade
you could not grade
she could not grade
we could not grade
you could not grade
they could not grade 	I could not be grading
you could not be grading
she could not be grading
we could not be grading
you could not be grading
they could not be grading	I could not have graded
you could not have graded
she could not have graded
we could not have graded
you could not have graded
they could not have graded	I could not have been grading
you could not have been grading
she could not have been grading
we could not have been grading
you could not have been grading
they could not have been grading	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I grade?
could you grade?
could she grade?
could we grade?
could you grade?
could they grade? 	could I be grading?
could you be grading?
could she be grading?
could we be grading?
could you be grading?
could they be grading? 	could I have graded?
could you have graded?
could she have graded?
could we have graded?
could you have graded?
could they have graded? 	could I have been grading?
could you have been grading?
could she have been grading?
could we have been grading?
could you have been grading?
could they have been grading? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not grade?
could you not grade?
could she not grade?
could we not grade?
could you not grade?
could they not grade? 	could I not be grading?
could you not be grading?
could she not be grading?
could we not be grading?
could you not be grading?
could they not be grading? 	could I not have graded?
could you not have graded?
could she not have graded?
could we not have graded?
could you not have graded?
could they not have graded? 	could I not have been grading?
could you not have been grading?
could she not have been grading?
could we not have been grading?
could you not have been grading?
could they not have been grading?