I can skim you can skim she can skim we can skim you can skim they can skim
V-ing form
I can be skimming you can be skimming she can be skimming we can be skimming you can be skimming they can be skimming
Perfect
I can have skimmed you can have skimmed she can have skimmed we can have skimmed you can have skimmed they can have skimmed
V-ing perfect
I can have been skimming you can have been skimming she can have been skimming we can have been skimming you can have been skimming they can have been skimming
Negation
Simple form
I cannot skim you cannot skim she cannot skim we cannot skim you cannot skim they cannot skim
V-ing form
I cannot be skimming you cannot be skimming she cannot be skimming we cannot be skimming you cannot be skimming they cannot be skimming
Perfect
I cannot have skimmed you cannot have skimmed she cannot have skimmed we cannot have skimmed you cannot have skimmed they cannot have skimmed
V-ing perfect
I cannot have been skimming you cannot have been skimming she cannot have been skimming we cannot have been skimming you cannot have been skimming they cannot have been skimming
Interrogative form
Simple form
can I skim? can you skim? can she skim? can we skim? can you skim? can they skim?
V-ing form
can I be skimming? can you be skimming? can she be skimming? can we be skimming? can you be skimming? can they be skimming?
Perfect
can I have skimmed? can you have skimmed? can she have skimmed? can we have skimmed? can you have skimmed? can they have skimmed?
V-ing perfect
can I have been skimming? can you have been skimming? can she have been skimming? can we have been skimming? can you have been skimming? can they have been skimming?
Interro-negative form
Simple form
can I not skim? can you not skim? can she not skim? can we not skim? can you not skim? can they not skim?
V-ing form
can I not be skimming? can you not be skimming? can she not be skimming? can we not be skimming? can you not be skimming? can they not be skimming?
Perfect
can I not have skimmed? can you not have skimmed? can she not have skimmed? can we not have skimmed? can you not have skimmed? can they not have skimmed?
V-ing perfect
can I not have been skimming? can you not have been skimming? can she not have been skimming? can we not have been skimming? can you not have been skimming? can they not have been skimming?