Halliday & Matthiessen (2014: 637):
As an alternative to the ellipsis of the whole clause, there may be ellipsis of just one part of it, the Residue. For example:||| Mum, you’re not enjoying your dinner, are you? ||| – ||| I am [∅: enjoying my dinner]. |||
||| I’ve had a headache. ||| – ||| Have you [∅: had a headache]? |||
||| Could you put your issue of Rapale literacy in the numeracy study. ||| – ||| Oh I suppose || I could [∅: put my issue of Rapale literacy in the numeracy study]. |||