English verb conjugation
COULD EXECUTE

Regular verb: execute - executed - executed

Affirmation

Simple form	V-ing form
I could execute you could execute he could execute we could execute you could execute they could execute	I could be executing you could be executing he could be executing we could be executing you could be executing they could be executing
Perfect	V-ing perfect
I could have executed you could have executed he could have executed we could have executed you could have executed they could have executed	I could have been executing you could have been executing he could have been executing we could have been executing you could have been executing they could have been executing

Negation

Simple form	V-ing form
I couldn't execute you couldn't execute he couldn't execute we couldn't execute you couldn't execute they couldn't execute	I couldn't be executing you couldn't be executing he couldn't be executing we couldn't be executing you couldn't be executing they couldn't be executing
Perfect	V-ing perfect
I couldn't have executed you couldn't have executed he couldn't have executed we couldn't have executed you couldn't have executed they couldn't have executed	I couldn't have been executing you couldn't have been executing he couldn't have been executing we couldn't have been executing you couldn't have been executing they couldn't have been executing

Interrogative form

Simple form	V-ing form
could I execute? could you execute? could he execute? could we execute? could you execute? could they execute?	could I be executing? could you be executing? could he be executing? could we be executing? could you be executing? could they be executing?
Perfect	V-ing perfect
could I have executed? could you have executed? could he have executed? could we have executed? could you have executed? could they have executed?	could I have been executing? could you have been executing? could he have been executing? could we have been executing? could you have been executing? could they have been executing?

Interro-negative form

Simple form	V-ing form
couldn't I execute? couldn't you execute? couldn't he execute? couldn't we execute? couldn't you execute? couldn't they execute?	couldn't I be executing? couldn't you be executing? couldn't he be executing? couldn't we be executing? couldn't you be executing? couldn't they be executing?
Perfect	V-ing perfect
couldn't I have executed? couldn't you have executed? couldn't he have executed? couldn't we have executed? couldn't you have executed? couldn't they have executed?	couldn't I have been executing? couldn't you have been executing? couldn't he have been executing? couldn't we have been executing? couldn't you have been executing? couldn't they have been executing?