English verb conjugation
COULD CONGRATULATE

Regular verb: congratulate - congratulated - congratulated

Affirmation

Simple form	V-ing form
I could congratulate you could congratulate he could congratulate we could congratulate you could congratulate they could congratulate	I could be congratulating you could be congratulating he could be congratulating we could be congratulating you could be congratulating they could be congratulating
Perfect	V-ing perfect
I could have congratulated you could have congratulated he could have congratulated we could have congratulated you could have congratulated they could have congratulated	I could have been congratulating you could have been congratulating he could have been congratulating we could have been congratulating you could have been congratulating they could have been congratulating

Negation

Simple form	V-ing form
I could not congratulate you could not congratulate he could not congratulate we could not congratulate you could not congratulate they could not congratulate	I could not be congratulating you could not be congratulating he could not be congratulating we could not be congratulating you could not be congratulating they could not be congratulating
Perfect	V-ing perfect
I could not have congratulated you could not have congratulated he could not have congratulated we could not have congratulated you could not have congratulated they could not have congratulated	I could not have been congratulating you could not have been congratulating he could not have been congratulating we could not have been congratulating you could not have been congratulating they could not have been congratulating

Interrogative form

Simple form	V-ing form
could I congratulate? could you congratulate? could he congratulate? could we congratulate? could you congratulate? could they congratulate?	could I be congratulating? could you be congratulating? could he be congratulating? could we be congratulating? could you be congratulating? could they be congratulating?
Perfect	V-ing perfect
could I have congratulated? could you have congratulated? could he have congratulated? could we have congratulated? could you have congratulated? could they have congratulated?	could I have been congratulating? could you have been congratulating? could he have been congratulating? could we have been congratulating? could you have been congratulating? could they have been congratulating?

Interro-negative form

Simple form	V-ing form
could I not congratulate? could you not congratulate? could he not congratulate? could we not congratulate? could you not congratulate? could they not congratulate?	could I not be congratulating? could you not be congratulating? could he not be congratulating? could we not be congratulating? could you not be congratulating? could they not be congratulating?
Perfect	V-ing perfect
could I not have congratulated? could you not have congratulated? could he not have congratulated? could we not have congratulated? could you not have congratulated? could they not have congratulated?	could I not have been congratulating? could you not have been congratulating? could he not have been congratulating? could we not have been congratulating? could you not have been congratulating? could they not have been congratulating?