I can skim you can skim he can skim we can skim you can skim they can skim
V-ing form
I can be skimming you can be skimming he can be skimming we can be skimming you can be skimming they can be skimming
Perfect
I can have skimmed you can have skimmed he 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 he can have been skimming we can have been skimming you can have been skimming they can have been skimming
Negation
Simple form
I can't skim you can't skim he can't skim we can't skim you can't skim they can't skim
V-ing form
I can't be skimming you can't be skimming he can't be skimming we can't be skimming you can't be skimming they can't be skimming
Perfect
I can't have skimmed you can't have skimmed he can't have skimmed we can't have skimmed you can't have skimmed they can't have skimmed
V-ing perfect
I can't have been skimming you can't have been skimming he can't have been skimming we can't have been skimming you can't have been skimming they can't have been skimming
Interrogative form
Simple form
can I skim? can you skim? can he skim? can we skim? can you skim? can they skim?
V-ing form
can I be skimming? can you be skimming? can he be skimming? can we be skimming? can you be skimming? can they be skimming?
Perfect
can I have skimmed? can you have skimmed? can he 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 he have been skimming? can we have been skimming? can you have been skimming? can they have been skimming?
Interro-negative form
Simple form
can't I skim? can't you skim? can't he skim? can't we skim? can't you skim? can't they skim?
V-ing form
can't I be skimming? can't you be skimming? can't he be skimming? can't we be skimming? can't you be skimming? can't they be skimming?
Perfect
can't I have skimmed? can't you have skimmed? can't he have skimmed? can't we have skimmed? can't you have skimmed? can't they have skimmed?
V-ing perfect
can't I have been skimming? can't you have been skimming? can't he have been skimming? can't we have been skimming? can't you have been skimming? can't they have been skimming?