English verb conjugation
COULD ECHO

Regular verb: echo - echoed - echoed

Affirmation

Simple form	V-ing form
I could echo you could echo she could echo we could echo you could echo they could echo	I could be echoing you could be echoing she 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 she 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 she 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 she 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 she 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 she 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 she 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 she echo? could we echo? could you echo? could they echo?	could I be echoing? could you be echoing? could she 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 she 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 she 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 she 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 she 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 she 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 she have been echoing? couldn't we have been echoing? couldn't you have been echoing? couldn't they have been echoing?