could machine
Regular verb: machine - machined- machined

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could machine
you could machine
he could machine
we could machine
you could machine
they could machine 	I could be machining
you could be machining
he could be machining
we could be machining
you could be machining
they could be machining	I could have machined
you could have machined
he could have machined
we could have machined
you could have machined
they could have machined	I could have been machining
you could have been machining
he could have been machining
we could have been machining
you could have been machining
they could have been machining	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't machine
you couldn't machine
he couldn't machine
we couldn't machine
you couldn't machine
they couldn't machine 	I couldn't be machining
you couldn't be machining
he couldn't be machining
we couldn't be machining
you couldn't be machining
they couldn't be machining	I couldn't have machined
you couldn't have machined
he couldn't have machined
we couldn't have machined
you couldn't have machined
they couldn't have machined	I couldn't have been machining
you couldn't have been machining
he couldn't have been machining
we couldn't have been machining
you couldn't have been machining
they couldn't have been machining	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I machine?
could you machine?
could he machine?
could we machine?
could you machine?
could they machine? 	could I be machining?
could you be machining?
could he be machining?
could we be machining?
could you be machining?
could they be machining? 	could I have machined?
could you have machined?
could he have machined?
could we have machined?
could you have machined?
could they have machined? 	could I have been machining?
could you have been machining?
could he have been machining?
could we have been machining?
could you have been machining?
could they have been machining? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I machine?
couldn't you machine?
couldn't he machine?
couldn't we machine?
couldn't you machine?
couldn't they machine? 	couldn't I be machining?
couldn't you be machining?
couldn't he be machining?
couldn't we be machining?
couldn't you be machining?
couldn't they be machining? 	couldn't I have machined?
couldn't you have machined?
couldn't he have machined?
couldn't we have machined?
couldn't you have machined?
couldn't they have machined? 	couldn't I have been machining?
couldn't you have been machining?
couldn't he have been machining?
couldn't we have been machining?
couldn't you have been machining?
couldn't they have been machining?