Hilary's answer is very helpful, but I don't think it answers your question. The answer to your question is 1, but not 2: we do not use too in a negative statement. For the same reason, Luiz's 4 and 5 are correct but 2 is not. His 1 isn't exactly wrong, but it is unusual, it would be better with 'nor' instead of 'so'. Similarly 'both' does not work well with a negative, 6 should be rewritten using 'neither'.

Hey icespirit, There are simpler ways to say this than the ones you provided. Here are some of them: 1) ''She is unable to swim, and so am I.'' 2) ''She is unable to swim, and I am too.'' 3) ''Not only is she unable to swim, but so/also am I.'' 4) ''She can't swim, and neither can I.'' 5) ''Neither she nor I are able to swim.'' 6) ''Both she and I are unable to swim.'' Hope that helps!!!

The simplest way to say this is "she can't swim, and neither can I".

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