How will a Do-So test help in identifying if a PP is an adjunct or complement to the verb? Example : I ran to work. I need two pieces of evidence to prove the status of PP in a sentence.
Recall that in English, adjunction is believed to look like this:
If the lower V' is a constituent, then we should expect it to be substitutable by 'do so' in the standard test, but we can't say that:
#I did so to work. (meaning 'I ran to work')
By contrast, you can substitute the whole thing 'ran to work' with do-so:
I went to work on Thursday.
I did so on Thursday.
This suggests that 'on Thursday' is an adjunct and 'to work' is the complement, i.e. this structure is appropriate: