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