English verb conjugation
COULD OBSERVE

Regular verb: observe - observed - observed

Affirmation

Simple form	V-ing form
I could observe you could observe she could observe we could observe you could observe they could observe	I could be observing you could be observing she could be observing we could be observing you could be observing they could be observing
Perfect	V-ing perfect
I could have observed you could have observed she could have observed we could have observed you could have observed they could have observed	I could have been observing you could have been observing she could have been observing we could have been observing you could have been observing they could have been observing

Negation

Simple form	V-ing form
I couldn't observe you couldn't observe she couldn't observe we couldn't observe you couldn't observe they couldn't observe	I couldn't be observing you couldn't be observing she couldn't be observing we couldn't be observing you couldn't be observing they couldn't be observing
Perfect	V-ing perfect
I couldn't have observed you couldn't have observed she couldn't have observed we couldn't have observed you couldn't have observed they couldn't have observed	I couldn't have been observing you couldn't have been observing she couldn't have been observing we couldn't have been observing you couldn't have been observing they couldn't have been observing

Interrogative form

Simple form	V-ing form
could I observe? could you observe? could she observe? could we observe? could you observe? could they observe?	could I be observing? could you be observing? could she be observing? could we be observing? could you be observing? could they be observing?
Perfect	V-ing perfect
could I have observed? could you have observed? could she have observed? could we have observed? could you have observed? could they have observed?	could I have been observing? could you have been observing? could she have been observing? could we have been observing? could you have been observing? could they have been observing?

Interro-negative form

Simple form	V-ing form
couldn't I observe? couldn't you observe? couldn't she observe? couldn't we observe? couldn't you observe? couldn't they observe?	couldn't I be observing? couldn't you be observing? couldn't she be observing? couldn't we be observing? couldn't you be observing? couldn't they be observing?
Perfect	V-ing perfect
couldn't I have observed? couldn't you have observed? couldn't she have observed? couldn't we have observed? couldn't you have observed? couldn't they have observed?	couldn't I have been observing? couldn't you have been observing? couldn't she have been observing? couldn't we have been observing? couldn't you have been observing? couldn't they have been observing?