I could twinkle you could twinkle he could twinkle we could twinkle you could twinkle they could twinkle
V-ing form
I could be twinkling you could be twinkling he could be twinkling we could be twinkling you could be twinkling they could be twinkling
Perfect
I could have twinkled you could have twinkled he could have twinkled we could have twinkled you could have twinkled they could have twinkled
V-ing perfect
I could have been twinkling you could have been twinkling he could have been twinkling we could have been twinkling you could have been twinkling they could have been twinkling
Negation
Simple form
I could not twinkle you could not twinkle he could not twinkle we could not twinkle you could not twinkle they could not twinkle
V-ing form
I could not be twinkling you could not be twinkling he could not be twinkling we could not be twinkling you could not be twinkling they could not be twinkling
Perfect
I could not have twinkled you could not have twinkled he could not have twinkled we could not have twinkled you could not have twinkled they could not have twinkled
V-ing perfect
I could not have been twinkling you could not have been twinkling he could not have been twinkling we could not have been twinkling you could not have been twinkling they could not have been twinkling
Interrogative form
Simple form
could I twinkle? could you twinkle? could he twinkle? could we twinkle? could you twinkle? could they twinkle?
V-ing form
could I be twinkling? could you be twinkling? could he be twinkling? could we be twinkling? could you be twinkling? could they be twinkling?
Perfect
could I have twinkled? could you have twinkled? could he have twinkled? could we have twinkled? could you have twinkled? could they have twinkled?
V-ing perfect
could I have been twinkling? could you have been twinkling? could he have been twinkling? could we have been twinkling? could you have been twinkling? could they have been twinkling?
Interro-negative form
Simple form
could I not twinkle? could you not twinkle? could he not twinkle? could we not twinkle? could you not twinkle? could they not twinkle?
V-ing form
could I not be twinkling? could you not be twinkling? could he not be twinkling? could we not be twinkling? could you not be twinkling? could they not be twinkling?
Perfect
could I not have twinkled? could you not have twinkled? could he not have twinkled? could we not have twinkled? could you not have twinkled? could they not have twinkled?
V-ing perfect
could I not have been twinkling? could you not have been twinkling? could he not have been twinkling? could we not have been twinkling? could you not have been twinkling? could they not have been twinkling?