I can sip you can sip he can sip we can sip you can sip they can sip
V-ing form
I can be sipping you can be sipping he can be sipping we can be sipping you can be sipping they can be sipping
Perfect
I can have sipped you can have sipped he can have sipped we can have sipped you can have sipped they can have sipped
V-ing perfect
I can have been sipping you can have been sipping he can have been sipping we can have been sipping you can have been sipping they can have been sipping
Negation
Simple form
I can't sip you can't sip he can't sip we can't sip you can't sip they can't sip
V-ing form
I can't be sipping you can't be sipping he can't be sipping we can't be sipping you can't be sipping they can't be sipping
Perfect
I can't have sipped you can't have sipped he can't have sipped we can't have sipped you can't have sipped they can't have sipped
V-ing perfect
I can't have been sipping you can't have been sipping he can't have been sipping we can't have been sipping you can't have been sipping they can't have been sipping
Interrogative form
Simple form
can I sip? can you sip? can he sip? can we sip? can you sip? can they sip?
V-ing form
can I be sipping? can you be sipping? can he be sipping? can we be sipping? can you be sipping? can they be sipping?
Perfect
can I have sipped? can you have sipped? can he have sipped? can we have sipped? can you have sipped? can they have sipped?
V-ing perfect
can I have been sipping? can you have been sipping? can he have been sipping? can we have been sipping? can you have been sipping? can they have been sipping?
Interro-negative form
Simple form
can't I sip? can't you sip? can't he sip? can't we sip? can't you sip? can't they sip?
V-ing form
can't I be sipping? can't you be sipping? can't he be sipping? can't we be sipping? can't you be sipping? can't they be sipping?
Perfect
can't I have sipped? can't you have sipped? can't he have sipped? can't we have sipped? can't you have sipped? can't they have sipped?
V-ing perfect
can't I have been sipping? can't you have been sipping? can't he have been sipping? can't we have been sipping? can't you have been sipping? can't they have been sipping?