could sham
Regular verb: sham - shammed- shammed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could sham
you could sham
he could sham
we could sham
you could sham
they could sham 	I could be shamming
you could be shamming
he could be shamming
we could be shamming
you could be shamming
they could be shamming	I could have shammed
you could have shammed
he could have shammed
we could have shammed
you could have shammed
they could have shammed	I could have been shamming
you could have been shamming
he could have been shamming
we could have been shamming
you could have been shamming
they could have been shamming	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not sham
you could not sham
he could not sham
we could not sham
you could not sham
they could not sham 	I could not be shamming
you could not be shamming
he could not be shamming
we could not be shamming
you could not be shamming
they could not be shamming	I could not have shammed
you could not have shammed
he could not have shammed
we could not have shammed
you could not have shammed
they could not have shammed	I could not have been shamming
you could not have been shamming
he could not have been shamming
we could not have been shamming
you could not have been shamming
they could not have been shamming	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I sham?
could you sham?
could he sham?
could we sham?
could you sham?
could they sham? 	could I be shamming?
could you be shamming?
could he be shamming?
could we be shamming?
could you be shamming?
could they be shamming? 	could I have shammed?
could you have shammed?
could he have shammed?
could we have shammed?
could you have shammed?
could they have shammed? 	could I have been shamming?
could you have been shamming?
could he have been shamming?
could we have been shamming?
could you have been shamming?
could they have been shamming? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not sham?
could you not sham?
could he not sham?
could we not sham?
could you not sham?
could they not sham? 	could I not be shamming?
could you not be shamming?
could he not be shamming?
could we not be shamming?
could you not be shamming?
could they not be shamming? 	could I not have shammed?
could you not have shammed?
could he not have shammed?
could we not have shammed?
could you not have shammed?
could they not have shammed? 	could I not have been shamming?
could you not have been shamming?
could he not have been shamming?
could we not have been shamming?
could you not have been shamming?
could they not have been shamming?