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