Additions with so, neither/nor, but Have a look at the following sentences: My father can sing very well, and so can my mother. My father can sing very well, but my aunt can’t. My father doesn’t like oysters, and neither/nor does my mother. My father doesn’t like oysters, but I do.
We are going to have a closer look at the underlined structures. “So” and “neither/nor” express agreement with the previous sentence, “but” expresses disagreement. There are several possibilities, depending on whether you start from a positive or a negative sentence. All possibilities are shown in these schemes:
Additions with so, neither/nor, but
STARTING FROM A POSITIVE SENTENCE: You start from a positive sentence eg. My father can sing very well You want to add another positive sentence (= “agreement”) → (and) so + auxiliary + subject eg. and so can my mother. You want to add a negative sentence (= “disagreement”) → but + subject + negative auxiliary eg. but my aunt can’t.