Halliday & Matthiessen (2014: 640):
Substitution in the verbal group is by means of the verb do, which can substitute for any verb provided it is active not passive, except be or, in some contexts, have. The verb do will appear in the appropriate non-finite form (do, doing, done). Examples:Does it hurt? –Not any more. It was doing last night.
Yeah but I’m doing night shift too. If I have to teach people on night shift as I have done, I do night shift and then I do day shift and get a couple of hours off and then do night shift and day shift.
As we have seen, this do typically substitutes for the whole of the Residue (or, what amounts to the same thing, when the verb is substituted by do, the rest of the Residue is ellipsed). Since there are no demonstrative verbs – we cannot say he thatted, he whatted? – this need is met by combining the verb substitute do with demonstratives that, what (serving as Range in the transitivity structure). For example:I did cross-eye in the middle of my art. – I can’t do that. – I can.
What did your father do? – He was an architect.
What are you going to do with Blubba? – Oh, I don’t know.
This is one thing I haven’t worked out with this phone whether, cause my old phone used to ring you to let you know you had a message. – Yeah. Does this one not do it?
The form do not functions as a single reference item.