could shift
Regular verb: shift - shifted- shifted

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could shift
you could shift
she could shift
we could shift
you could shift
they could shift 	I could be shifting
you could be shifting
she could be shifting
we could be shifting
you could be shifting
they could be shifting	I could have shifted
you could have shifted
she could have shifted
we could have shifted
you could have shifted
they could have shifted	I could have been shifting
you could have been shifting
she could have been shifting
we could have been shifting
you could have been shifting
they could have been shifting	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't shift
you couldn't shift
she couldn't shift
we couldn't shift
you couldn't shift
they couldn't shift 	I couldn't be shifting
you couldn't be shifting
she couldn't be shifting
we couldn't be shifting
you couldn't be shifting
they couldn't be shifting	I couldn't have shifted
you couldn't have shifted
she couldn't have shifted
we couldn't have shifted
you couldn't have shifted
they couldn't have shifted	I couldn't have been shifting
you couldn't have been shifting
she couldn't have been shifting
we couldn't have been shifting
you couldn't have been shifting
they couldn't have been shifting	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I shift?
could you shift?
could she shift?
could we shift?
could you shift?
could they shift? 	could I be shifting?
could you be shifting?
could she be shifting?
could we be shifting?
could you be shifting?
could they be shifting? 	could I have shifted?
could you have shifted?
could she have shifted?
could we have shifted?
could you have shifted?
could they have shifted? 	could I have been shifting?
could you have been shifting?
could she have been shifting?
could we have been shifting?
could you have been shifting?
could they have been shifting? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I shift?
couldn't you shift?
couldn't she shift?
couldn't we shift?
couldn't you shift?
couldn't they shift? 	couldn't I be shifting?
couldn't you be shifting?
couldn't she be shifting?
couldn't we be shifting?
couldn't you be shifting?
couldn't they be shifting? 	couldn't I have shifted?
couldn't you have shifted?
couldn't she have shifted?
couldn't we have shifted?
couldn't you have shifted?
couldn't they have shifted? 	couldn't I have been shifting?
couldn't you have been shifting?
couldn't she have been shifting?
couldn't we have been shifting?
couldn't you have been shifting?
couldn't they have been shifting?