English verb conjugation
COULD DIPHTHONGIZE

Regular verb: diphthongize - diphthongized - diphthongized

Affirmation

Simple form	V-ing form
I could diphthongize you could diphthongize he could diphthongize we could diphthongize you could diphthongize they could diphthongize	I could be diphthongizing you could be diphthongizing he could be diphthongizing we could be diphthongizing you could be diphthongizing they could be diphthongizing
Perfect	V-ing perfect
I could have diphthongized you could have diphthongized he could have diphthongized we could have diphthongized you could have diphthongized they could have diphthongized	I could have been diphthongizing you could have been diphthongizing he could have been diphthongizing we could have been diphthongizing you could have been diphthongizing they could have been diphthongizing

Negation

Simple form	V-ing form
I couldn't diphthongize you couldn't diphthongize he couldn't diphthongize we couldn't diphthongize you couldn't diphthongize they couldn't diphthongize	I couldn't be diphthongizing you couldn't be diphthongizing he couldn't be diphthongizing we couldn't be diphthongizing you couldn't be diphthongizing they couldn't be diphthongizing
Perfect	V-ing perfect
I couldn't have diphthongized you couldn't have diphthongized he couldn't have diphthongized we couldn't have diphthongized you couldn't have diphthongized they couldn't have diphthongized	I couldn't have been diphthongizing you couldn't have been diphthongizing he couldn't have been diphthongizing we couldn't have been diphthongizing you couldn't have been diphthongizing they couldn't have been diphthongizing

Interrogative form

Simple form	V-ing form
could I diphthongize? could you diphthongize? could he diphthongize? could we diphthongize? could you diphthongize? could they diphthongize?	could I be diphthongizing? could you be diphthongizing? could he be diphthongizing? could we be diphthongizing? could you be diphthongizing? could they be diphthongizing?
Perfect	V-ing perfect
could I have diphthongized? could you have diphthongized? could he have diphthongized? could we have diphthongized? could you have diphthongized? could they have diphthongized?	could I have been diphthongizing? could you have been diphthongizing? could he have been diphthongizing? could we have been diphthongizing? could you have been diphthongizing? could they have been diphthongizing?

Interro-negative form

Simple form	V-ing form
couldn't I diphthongize? couldn't you diphthongize? couldn't he diphthongize? couldn't we diphthongize? couldn't you diphthongize? couldn't they diphthongize?	couldn't I be diphthongizing? couldn't you be diphthongizing? couldn't he be diphthongizing? couldn't we be diphthongizing? couldn't you be diphthongizing? couldn't they be diphthongizing?
Perfect	V-ing perfect
couldn't I have diphthongized? couldn't you have diphthongized? couldn't he have diphthongized? couldn't we have diphthongized? couldn't you have diphthongized? couldn't they have diphthongized?	couldn't I have been diphthongizing? couldn't you have been diphthongizing? couldn't he have been diphthongizing? couldn't we have been diphthongizing? couldn't you have been diphthongizing? couldn't they have been diphthongizing?