English verb conjugation
COULD DIPHTHONGIZE

Regular verb: diphthongize - diphthongized - diphthongized

Affirmation

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