I could contaminate you could contaminate she could contaminate we could contaminate you could contaminate they could contaminate
V-ing form
I could be contaminating you could be contaminating she could be contaminating we could be contaminating you could be contaminating they could be contaminating
Perfect
I could have contaminated you could have contaminated she could have contaminated we could have contaminated you could have contaminated they could have contaminated
V-ing perfect
I could have been contaminating you could have been contaminating she could have been contaminating we could have been contaminating you could have been contaminating they could have been contaminating
Negation
Simple form
I couldn't contaminate you couldn't contaminate she couldn't contaminate we couldn't contaminate you couldn't contaminate they couldn't contaminate
V-ing form
I couldn't be contaminating you couldn't be contaminating she couldn't be contaminating we couldn't be contaminating you couldn't be contaminating they couldn't be contaminating
Perfect
I couldn't have contaminated you couldn't have contaminated she couldn't have contaminated we couldn't have contaminated you couldn't have contaminated they couldn't have contaminated
V-ing perfect
I couldn't have been contaminating you couldn't have been contaminating she couldn't have been contaminating we couldn't have been contaminating you couldn't have been contaminating they couldn't have been contaminating
Interrogative form
Simple form
could I contaminate? could you contaminate? could she contaminate? could we contaminate? could you contaminate? could they contaminate?
V-ing form
could I be contaminating? could you be contaminating? could she be contaminating? could we be contaminating? could you be contaminating? could they be contaminating?
Perfect
could I have contaminated? could you have contaminated? could she have contaminated? could we have contaminated? could you have contaminated? could they have contaminated?
V-ing perfect
could I have been contaminating? could you have been contaminating? could she have been contaminating? could we have been contaminating? could you have been contaminating? could they have been contaminating?
Interro-negative form
Simple form
couldn't I contaminate? couldn't you contaminate? couldn't she contaminate? couldn't we contaminate? couldn't you contaminate? couldn't they contaminate?
V-ing form
couldn't I be contaminating? couldn't you be contaminating? couldn't she be contaminating? couldn't we be contaminating? couldn't you be contaminating? couldn't they be contaminating?
Perfect
couldn't I have contaminated? couldn't you have contaminated? couldn't she have contaminated? couldn't we have contaminated? couldn't you have contaminated? couldn't they have contaminated?
V-ing perfect
couldn't I have been contaminating? couldn't you have been contaminating? couldn't she have been contaminating? couldn't we have been contaminating? couldn't you have been contaminating? couldn't they have been contaminating?