I could labor you could labor she could labor we could labor you could labor they could labor
V-ing form
I could be laboring you could be laboring she could be laboring we could be laboring you could be laboring they could be laboring
Perfect
I could have labored you could have labored she could have labored we could have labored you could have labored they could have labored
V-ing perfect
I could have been laboring you could have been laboring she could have been laboring we could have been laboring you could have been laboring they could have been laboring
Negation
Simple form
I could not labor you could not labor she could not labor we could not labor you could not labor they could not labor
V-ing form
I could not be laboring you could not be laboring she could not be laboring we could not be laboring you could not be laboring they could not be laboring
Perfect
I could not have labored you could not have labored she could not have labored we could not have labored you could not have labored they could not have labored
V-ing perfect
I could not have been laboring you could not have been laboring she could not have been laboring we could not have been laboring you could not have been laboring they could not have been laboring
Interrogative form
Simple form
could I labor? could you labor? could she labor? could we labor? could you labor? could they labor?
V-ing form
could I be laboring? could you be laboring? could she be laboring? could we be laboring? could you be laboring? could they be laboring?
Perfect
could I have labored? could you have labored? could she have labored? could we have labored? could you have labored? could they have labored?
V-ing perfect
could I have been laboring? could you have been laboring? could she have been laboring? could we have been laboring? could you have been laboring? could they have been laboring?
Interro-negative form
Simple form
could I not labor? could you not labor? could she not labor? could we not labor? could you not labor? could they not labor?
V-ing form
could I not be laboring? could you not be laboring? could she not be laboring? could we not be laboring? could you not be laboring? could they not be laboring?
Perfect
could I not have labored? could you not have labored? could she not have labored? could we not have labored? could you not have labored? could they not have labored?
V-ing perfect
could I not have been laboring? could you not have been laboring? could she not have been laboring? could we not have been laboring? could you not have been laboring? could they not have been laboring?