English verb conjugation
COULD ECHO

Regular verb: echo - echoed - echoed

Affirmation

Simple form	V-ing form
I could echo you could echo he could echo we could echo you could echo they could echo	I could be echoing you could be echoing he could be echoing we could be echoing you could be echoing they could be echoing
Perfect	V-ing perfect
I could have echoed you could have echoed he could have echoed we could have echoed you could have echoed they could have echoed	I could have been echoing you could have been echoing he could have been echoing we could have been echoing you could have been echoing they could have been echoing

Negation

Simple form	V-ing form
I couldn't echo you couldn't echo he couldn't echo we couldn't echo you couldn't echo they couldn't echo	I couldn't be echoing you couldn't be echoing he couldn't be echoing we couldn't be echoing you couldn't be echoing they couldn't be echoing
Perfect	V-ing perfect
I couldn't have echoed you couldn't have echoed he couldn't have echoed we couldn't have echoed you couldn't have echoed they couldn't have echoed	I couldn't have been echoing you couldn't have been echoing he couldn't have been echoing we couldn't have been echoing you couldn't have been echoing they couldn't have been echoing

Interrogative form

Simple form	V-ing form
could I echo? could you echo? could he echo? could we echo? could you echo? could they echo?	could I be echoing? could you be echoing? could he be echoing? could we be echoing? could you be echoing? could they be echoing?
Perfect	V-ing perfect
could I have echoed? could you have echoed? could he have echoed? could we have echoed? could you have echoed? could they have echoed?	could I have been echoing? could you have been echoing? could he have been echoing? could we have been echoing? could you have been echoing? could they have been echoing?

Interro-negative form

Simple form	V-ing form
couldn't I echo? couldn't you echo? couldn't he echo? couldn't we echo? couldn't you echo? couldn't they echo?	couldn't I be echoing? couldn't you be echoing? couldn't he be echoing? couldn't we be echoing? couldn't you be echoing? couldn't they be echoing?
Perfect	V-ing perfect
couldn't I have echoed? couldn't you have echoed? couldn't he have echoed? couldn't we have echoed? couldn't you have echoed? couldn't they have echoed?	couldn't I have been echoing? couldn't you have been echoing? couldn't he have been echoing? couldn't we have been echoing? couldn't you have been echoing? couldn't they have been echoing?