could high-grade
Regular verb: high-grade - high-graded- high-graded

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

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

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

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