I can sire you can sire he can sire we can sire you can sire they can sire
V-ing form
I can be siring you can be siring he can be siring we can be siring you can be siring they can be siring
Perfect
I can have sired you can have sired he can have sired we can have sired you can have sired they can have sired
V-ing perfect
I can have been siring you can have been siring he can have been siring we can have been siring you can have been siring they can have been siring
Negation
Simple form
I can't sire you can't sire he can't sire we can't sire you can't sire they can't sire
V-ing form
I can't be siring you can't be siring he can't be siring we can't be siring you can't be siring they can't be siring
Perfect
I can't have sired you can't have sired he can't have sired we can't have sired you can't have sired they can't have sired
V-ing perfect
I can't have been siring you can't have been siring he can't have been siring we can't have been siring you can't have been siring they can't have been siring
Interrogative form
Simple form
can I sire? can you sire? can he sire? can we sire? can you sire? can they sire?
V-ing form
can I be siring? can you be siring? can he be siring? can we be siring? can you be siring? can they be siring?
Perfect
can I have sired? can you have sired? can he have sired? can we have sired? can you have sired? can they have sired?
V-ing perfect
can I have been siring? can you have been siring? can he have been siring? can we have been siring? can you have been siring? can they have been siring?
Interro-negative form
Simple form
can't I sire? can't you sire? can't he sire? can't we sire? can't you sire? can't they sire?
V-ing form
can't I be siring? can't you be siring? can't he be siring? can't we be siring? can't you be siring? can't they be siring?
Perfect
can't I have sired? can't you have sired? can't he have sired? can't we have sired? can't you have sired? can't they have sired?
V-ing perfect
can't I have been siring? can't you have been siring? can't he have been siring? can't we have been siring? can't you have been siring? can't they have been siring?