English verb conjugation
COULD MAST

Regular verb: mast - masted - masted

Affirmation

Simple form	V-ing form
I could mast you could mast he could mast we could mast you could mast they could mast	I could be masting you could be masting he could be masting we could be masting you could be masting they could be masting
Perfect	V-ing perfect
I could have masted you could have masted he could have masted we could have masted you could have masted they could have masted	I could have been masting you could have been masting he could have been masting we could have been masting you could have been masting they could have been masting

Negation

Simple form	V-ing form
I couldn't mast you couldn't mast he couldn't mast we couldn't mast you couldn't mast they couldn't mast	I couldn't be masting you couldn't be masting he couldn't be masting we couldn't be masting you couldn't be masting they couldn't be masting
Perfect	V-ing perfect
I couldn't have masted you couldn't have masted he couldn't have masted we couldn't have masted you couldn't have masted they couldn't have masted	I couldn't have been masting you couldn't have been masting he couldn't have been masting we couldn't have been masting you couldn't have been masting they couldn't have been masting

Interrogative form

Simple form	V-ing form
could I mast? could you mast? could he mast? could we mast? could you mast? could they mast?	could I be masting? could you be masting? could he be masting? could we be masting? could you be masting? could they be masting?
Perfect	V-ing perfect
could I have masted? could you have masted? could he have masted? could we have masted? could you have masted? could they have masted?	could I have been masting? could you have been masting? could he have been masting? could we have been masting? could you have been masting? could they have been masting?

Interro-negative form

Simple form	V-ing form
couldn't I mast? couldn't you mast? couldn't he mast? couldn't we mast? couldn't you mast? couldn't they mast?	couldn't I be masting? couldn't you be masting? couldn't he be masting? couldn't we be masting? couldn't you be masting? couldn't they be masting?
Perfect	V-ing perfect
couldn't I have masted? couldn't you have masted? couldn't he have masted? couldn't we have masted? couldn't you have masted? couldn't they have masted?	couldn't I have been masting? couldn't you have been masting? couldn't he have been masting? couldn't we have been masting? couldn't you have been masting? couldn't they have been masting?