I can systematise you can systematise he can systematise we can systematise you can systematise they can systematise
V-ing form
I can be systematising you can be systematising he can be systematising we can be systematising you can be systematising they can be systematising
Perfect
I can have systematised you can have systematised he can have systematised we can have systematised you can have systematised they can have systematised
V-ing perfect
I can have been systematising you can have been systematising he can have been systematising we can have been systematising you can have been systematising they can have been systematising
Negation
Simple form
I can't systematise you can't systematise he can't systematise we can't systematise you can't systematise they can't systematise
V-ing form
I can't be systematising you can't be systematising he can't be systematising we can't be systematising you can't be systematising they can't be systematising
Perfect
I can't have systematised you can't have systematised he can't have systematised we can't have systematised you can't have systematised they can't have systematised
V-ing perfect
I can't have been systematising you can't have been systematising he can't have been systematising we can't have been systematising you can't have been systematising they can't have been systematising
Interrogative form
Simple form
can I systematise? can you systematise? can he systematise? can we systematise? can you systematise? can they systematise?
V-ing form
can I be systematising? can you be systematising? can he be systematising? can we be systematising? can you be systematising? can they be systematising?
Perfect
can I have systematised? can you have systematised? can he have systematised? can we have systematised? can you have systematised? can they have systematised?
V-ing perfect
can I have been systematising? can you have been systematising? can he have been systematising? can we have been systematising? can you have been systematising? can they have been systematising?
Interro-negative form
Simple form
can't I systematise? can't you systematise? can't he systematise? can't we systematise? can't you systematise? can't they systematise?
V-ing form
can't I be systematising? can't you be systematising? can't he be systematising? can't we be systematising? can't you be systematising? can't they be systematising?
Perfect
can't I have systematised? can't you have systematised? can't he have systematised? can't we have systematised? can't you have systematised? can't they have systematised?
V-ing perfect
can't I have been systematising? can't you have been systematising? can't he have been systematising? can't we have been systematising? can't you have been systematising? can't they have been systematising?