English verb conjugation
COULD DIAGNOSE

Regular verb: diagnose - diagnosed - diagnosed

Affirmation

Simple form	V-ing form
I could diagnose you could diagnose he could diagnose we could diagnose you could diagnose they could diagnose	I could be diagnosing you could be diagnosing he could be diagnosing we could be diagnosing you could be diagnosing they could be diagnosing
Perfect	V-ing perfect
I could have diagnosed you could have diagnosed he could have diagnosed we could have diagnosed you could have diagnosed they could have diagnosed	I could have been diagnosing you could have been diagnosing he could have been diagnosing we could have been diagnosing you could have been diagnosing they could have been diagnosing

Negation

Simple form	V-ing form
I couldn't diagnose you couldn't diagnose he couldn't diagnose we couldn't diagnose you couldn't diagnose they couldn't diagnose	I couldn't be diagnosing you couldn't be diagnosing he couldn't be diagnosing we couldn't be diagnosing you couldn't be diagnosing they couldn't be diagnosing
Perfect	V-ing perfect
I couldn't have diagnosed you couldn't have diagnosed he couldn't have diagnosed we couldn't have diagnosed you couldn't have diagnosed they couldn't have diagnosed	I couldn't have been diagnosing you couldn't have been diagnosing he couldn't have been diagnosing we couldn't have been diagnosing you couldn't have been diagnosing they couldn't have been diagnosing

Interrogative form

Simple form	V-ing form
could I diagnose? could you diagnose? could he diagnose? could we diagnose? could you diagnose? could they diagnose?	could I be diagnosing? could you be diagnosing? could he be diagnosing? could we be diagnosing? could you be diagnosing? could they be diagnosing?
Perfect	V-ing perfect
could I have diagnosed? could you have diagnosed? could he have diagnosed? could we have diagnosed? could you have diagnosed? could they have diagnosed?	could I have been diagnosing? could you have been diagnosing? could he have been diagnosing? could we have been diagnosing? could you have been diagnosing? could they have been diagnosing?

Interro-negative form

Simple form	V-ing form
couldn't I diagnose? couldn't you diagnose? couldn't he diagnose? couldn't we diagnose? couldn't you diagnose? couldn't they diagnose?	couldn't I be diagnosing? couldn't you be diagnosing? couldn't he be diagnosing? couldn't we be diagnosing? couldn't you be diagnosing? couldn't they be diagnosing?
Perfect	V-ing perfect
couldn't I have diagnosed? couldn't you have diagnosed? couldn't he have diagnosed? couldn't we have diagnosed? couldn't you have diagnosed? couldn't they have diagnosed?	couldn't I have been diagnosing? couldn't you have been diagnosing? couldn't he have been diagnosing? couldn't we have been diagnosing? couldn't you have been diagnosing? couldn't they have been diagnosing?