I could execute you could execute she could execute we could execute you could execute they could execute
V-ing form
I could be executing you could be executing she could be executing we could be executing you could be executing they could be executing
Perfect
I could have executed you could have executed she could have executed we could have executed you could have executed they could have executed
V-ing perfect
I could have been executing you could have been executing she could have been executing we could have been executing you could have been executing they could have been executing
Negation
Simple form
I could not execute you could not execute she could not execute we could not execute you could not execute they could not execute
V-ing form
I could not be executing you could not be executing she could not be executing we could not be executing you could not be executing they could not be executing
Perfect
I could not have executed you could not have executed she could not have executed we could not have executed you could not have executed they could not have executed
V-ing perfect
I could not have been executing you could not have been executing she could not have been executing we could not have been executing you could not have been executing they could not have been executing
Interrogative form
Simple form
could I execute? could you execute? could she execute? could we execute? could you execute? could they execute?
V-ing form
could I be executing? could you be executing? could she be executing? could we be executing? could you be executing? could they be executing?
Perfect
could I have executed? could you have executed? could she have executed? could we have executed? could you have executed? could they have executed?
V-ing perfect
could I have been executing? could you have been executing? could she have been executing? could we have been executing? could you have been executing? could they have been executing?
Interro-negative form
Simple form
could I not execute? could you not execute? could she not execute? could we not execute? could you not execute? could they not execute?
V-ing form
could I not be executing? could you not be executing? could she not be executing? could we not be executing? could you not be executing? could they not be executing?
Perfect
could I not have executed? could you not have executed? could she not have executed? could we not have executed? could you not have executed? could they not have executed?
V-ing perfect
could I not have been executing? could you not have been executing? could she not have been executing? could we not have been executing? could you not have been executing? could they not have been executing?