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