It's a failry recent usage- many don't like it. In b), you could say 'I so know the answer'. Older people tend to feel this is not the best English, but teenagers seemto love it. It's also used in British English.
It's a failry recent usage- many don't like it. In b), you could say 'I so know the answer'. Older people tend to feel this is not the best English, but teenagers seemto love it. It's also used in British English.