English verb conjugation
COULD DIPHTHONGISE

Regular verb: diphthongise - diphthongised - diphthongised

Affirmation

Simple form	V-ing form
I could diphthongise you could diphthongise he could diphthongise we could diphthongise you could diphthongise they could diphthongise	I could be diphthongising you could be diphthongising he could be diphthongising we could be diphthongising you could be diphthongising they could be diphthongising
Perfect	V-ing perfect
I could have diphthongised you could have diphthongised he could have diphthongised we could have diphthongised you could have diphthongised they could have diphthongised	I could have been diphthongising you could have been diphthongising he could have been diphthongising we could have been diphthongising you could have been diphthongising they could have been diphthongising

Negation

Simple form	V-ing form
I could not diphthongise you could not diphthongise he could not diphthongise we could not diphthongise you could not diphthongise they could not diphthongise	I could not be diphthongising you could not be diphthongising he could not be diphthongising we could not be diphthongising you could not be diphthongising they could not be diphthongising
Perfect	V-ing perfect
I could not have diphthongised you could not have diphthongised he could not have diphthongised we could not have diphthongised you could not have diphthongised they could not have diphthongised	I could not have been diphthongising you could not have been diphthongising he could not have been diphthongising we could not have been diphthongising you could not have been diphthongising they could not have been diphthongising

Interrogative form

Simple form	V-ing form
could I diphthongise? could you diphthongise? could he diphthongise? could we diphthongise? could you diphthongise? could they diphthongise?	could I be diphthongising? could you be diphthongising? could he be diphthongising? could we be diphthongising? could you be diphthongising? could they be diphthongising?
Perfect	V-ing perfect
could I have diphthongised? could you have diphthongised? could he have diphthongised? could we have diphthongised? could you have diphthongised? could they have diphthongised?	could I have been diphthongising? could you have been diphthongising? could he have been diphthongising? could we have been diphthongising? could you have been diphthongising? could they have been diphthongising?

Interro-negative form

Simple form	V-ing form
could I not diphthongise? could you not diphthongise? could he not diphthongise? could we not diphthongise? could you not diphthongise? could they not diphthongise?	could I not be diphthongising? could you not be diphthongising? could he not be diphthongising? could we not be diphthongising? could you not be diphthongising? could they not be diphthongising?
Perfect	V-ing perfect
could I not have diphthongised? could you not have diphthongised? could he not have diphthongised? could we not have diphthongised? could you not have diphthongised? could they not have diphthongised?	could I not have been diphthongising? could you not have been diphthongising? could he not have been diphthongising? could we not have been diphthongising? could you not have been diphthongising? could they not have been diphthongising?