I can boast you can boast he can boast we can boast you can boast they can boast
V-ing form
I can be boasting you can be boasting he can be boasting we can be boasting you can be boasting they can be boasting
Perfect
I can have boasted you can have boasted he can have boasted we can have boasted you can have boasted they can have boasted
V-ing perfect
I can have been boasting you can have been boasting he can have been boasting we can have been boasting you can have been boasting they can have been boasting
Negation
Simple form
I can't boast you can't boast he can't boast we can't boast you can't boast they can't boast
V-ing form
I can't be boasting you can't be boasting he can't be boasting we can't be boasting you can't be boasting they can't be boasting
Perfect
I can't have boasted you can't have boasted he can't have boasted we can't have boasted you can't have boasted they can't have boasted
V-ing perfect
I can't have been boasting you can't have been boasting he can't have been boasting we can't have been boasting you can't have been boasting they can't have been boasting
Interrogative form
Simple form
can I boast? can you boast? can he boast? can we boast? can you boast? can they boast?
V-ing form
can I be boasting? can you be boasting? can he be boasting? can we be boasting? can you be boasting? can they be boasting?
Perfect
can I have boasted? can you have boasted? can he have boasted? can we have boasted? can you have boasted? can they have boasted?
V-ing perfect
can I have been boasting? can you have been boasting? can he have been boasting? can we have been boasting? can you have been boasting? can they have been boasting?
Interro-negative form
Simple form
can't I boast? can't you boast? can't he boast? can't we boast? can't you boast? can't they boast?
V-ing form
can't I be boasting? can't you be boasting? can't he be boasting? can't we be boasting? can't you be boasting? can't they be boasting?
Perfect
can't I have boasted? can't you have boasted? can't he have boasted? can't we have boasted? can't you have boasted? can't they have boasted?
V-ing perfect
can't I have been boasting? can't you have been boasting? can't he have been boasting? can't we have been boasting? can't you have been boasting? can't they have been boasting?