I could labor you could labor he could labor we could labor you could labor they could labor
V-ing form
I could be laboring you could be laboring he could be laboring we could be laboring you could be laboring they could be laboring
Perfect
I could have labored you could have labored he 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 he could have been laboring we could have been laboring you could have been laboring they could have been laboring
Negation
Simple form
I couldn't labor you couldn't labor he couldn't labor we couldn't labor you couldn't labor they couldn't labor
V-ing form
I couldn't be laboring you couldn't be laboring he couldn't be laboring we couldn't be laboring you couldn't be laboring they couldn't be laboring
Perfect
I couldn't have labored you couldn't have labored he couldn't have labored we couldn't have labored you couldn't have labored they couldn't have labored
V-ing perfect
I couldn't have been laboring you couldn't have been laboring he couldn't have been laboring we couldn't have been laboring you couldn't have been laboring they couldn't have been laboring
Interrogative form
Simple form
could I labor? could you labor? could he labor? could we labor? could you labor? could they labor?
V-ing form
could I be laboring? could you be laboring? could he be laboring? could we be laboring? could you be laboring? could they be laboring?
Perfect
could I have labored? could you have labored? could he 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 he have been laboring? could we have been laboring? could you have been laboring? could they have been laboring?
Interro-negative form
Simple form
couldn't I labor? couldn't you labor? couldn't he labor? couldn't we labor? couldn't you labor? couldn't they labor?
V-ing form
couldn't I be laboring? couldn't you be laboring? couldn't he be laboring? couldn't we be laboring? couldn't you be laboring? couldn't they be laboring?
Perfect
couldn't I have labored? couldn't you have labored? couldn't he have labored? couldn't we have labored? couldn't you have labored? couldn't they have labored?
V-ing perfect
couldn't I have been laboring? couldn't you have been laboring? couldn't he have been laboring? couldn't we have been laboring? couldn't you have been laboring? couldn't they have been laboring?