I can grab you can grab he can grab we can grab you can grab they can grab
V-ing form
I can be grabbing you can be grabbing he can be grabbing we can be grabbing you can be grabbing they can be grabbing
Perfect
I can have grabbed you can have grabbed he can have grabbed we can have grabbed you can have grabbed they can have grabbed
V-ing perfect
I can have been grabbing you can have been grabbing he can have been grabbing we can have been grabbing you can have been grabbing they can have been grabbing
Negation
Simple form
I can't grab you can't grab he can't grab we can't grab you can't grab they can't grab
V-ing form
I can't be grabbing you can't be grabbing he can't be grabbing we can't be grabbing you can't be grabbing they can't be grabbing
Perfect
I can't have grabbed you can't have grabbed he can't have grabbed we can't have grabbed you can't have grabbed they can't have grabbed
V-ing perfect
I can't have been grabbing you can't have been grabbing he can't have been grabbing we can't have been grabbing you can't have been grabbing they can't have been grabbing
Interrogative form
Simple form
can I grab? can you grab? can he grab? can we grab? can you grab? can they grab?
V-ing form
can I be grabbing? can you be grabbing? can he be grabbing? can we be grabbing? can you be grabbing? can they be grabbing?
Perfect
can I have grabbed? can you have grabbed? can he have grabbed? can we have grabbed? can you have grabbed? can they have grabbed?
V-ing perfect
can I have been grabbing? can you have been grabbing? can he have been grabbing? can we have been grabbing? can you have been grabbing? can they have been grabbing?
Interro-negative form
Simple form
can't I grab? can't you grab? can't he grab? can't we grab? can't you grab? can't they grab?
V-ing form
can't I be grabbing? can't you be grabbing? can't he be grabbing? can't we be grabbing? can't you be grabbing? can't they be grabbing?
Perfect
can't I have grabbed? can't you have grabbed? can't he have grabbed? can't we have grabbed? can't you have grabbed? can't they have grabbed?
V-ing perfect
can't I have been grabbing? can't you have been grabbing? can't he have been grabbing? can't we have been grabbing? can't you have been grabbing? can't they have been grabbing?