English verb conjugation
COULD STRATIFY

Regular verb: stratify - stratified - stratified

Affirmation

Simple form	V-ing form
I could stratify you could stratify he could stratify we could stratify you could stratify they could stratify	I could be stratifying you could be stratifying he could be stratifying we could be stratifying you could be stratifying they could be stratifying
Perfect	V-ing perfect
I could have stratified you could have stratified he could have stratified we could have stratified you could have stratified they could have stratified	I could have been stratifying you could have been stratifying he could have been stratifying we could have been stratifying you could have been stratifying they could have been stratifying

Negation

Simple form	V-ing form
I couldn't stratify you couldn't stratify he couldn't stratify we couldn't stratify you couldn't stratify they couldn't stratify	I couldn't be stratifying you couldn't be stratifying he couldn't be stratifying we couldn't be stratifying you couldn't be stratifying they couldn't be stratifying
Perfect	V-ing perfect
I couldn't have stratified you couldn't have stratified he couldn't have stratified we couldn't have stratified you couldn't have stratified they couldn't have stratified	I couldn't have been stratifying you couldn't have been stratifying he couldn't have been stratifying we couldn't have been stratifying you couldn't have been stratifying they couldn't have been stratifying

Interrogative form

Simple form	V-ing form
could I stratify? could you stratify? could he stratify? could we stratify? could you stratify? could they stratify?	could I be stratifying? could you be stratifying? could he be stratifying? could we be stratifying? could you be stratifying? could they be stratifying?
Perfect	V-ing perfect
could I have stratified? could you have stratified? could he have stratified? could we have stratified? could you have stratified? could they have stratified?	could I have been stratifying? could you have been stratifying? could he have been stratifying? could we have been stratifying? could you have been stratifying? could they have been stratifying?

Interro-negative form

Simple form	V-ing form
couldn't I stratify? couldn't you stratify? couldn't he stratify? couldn't we stratify? couldn't you stratify? couldn't they stratify?	couldn't I be stratifying? couldn't you be stratifying? couldn't he be stratifying? couldn't we be stratifying? couldn't you be stratifying? couldn't they be stratifying?
Perfect	V-ing perfect
couldn't I have stratified? couldn't you have stratified? couldn't he have stratified? couldn't we have stratified? couldn't you have stratified? couldn't they have stratified?	couldn't I have been stratifying? couldn't you have been stratifying? couldn't he have been stratifying? couldn't we have been stratifying? couldn't you have been stratifying? couldn't they have been stratifying?