Proto-Kangshuic had several ways of forming subordinate clauses. Many of them used the light copula -k as a syntactic basis.
Relative clauses in Proto-Kangshuic were generally formed by preceding a full VP with a light copula inflected to agree with the extraposed subject of the VP. Thus:
Gàpˀ lˀùn źék ʒɤ́k kúkòprág
gàpˀman lˀùnfish źékCLF ʒɤ́kone kú-3s.AN.TA-kò-3s.AN.TP.REAL.PFV-prágcatch
"The man caught one fish"
Gàpˀ ḥák lˀùn źék ʒɤ́k kúkòprág qàráṃ kúkòdɯ́lˀ
gàpˀman ḥá-3s.AN.IA-kCOP lˀùnfish źékCLF ʒɤ́kone kú-3s.AN.TA-kò-3s.AN.TP.REAL.PFV-prágcatch qàrámprize kú-3s.AN.TA-kò-3s.AN.TP.REAL.PFV-dɯ́lˀreceive
"The man who caught one fish received a prize"
Nominalized clauses are a pervasive feature of Proto-Kangshuic syntax. They are formed similarly to relative clauses, but they take the noun mwòˀ "fact, thing" as a head and inflect for the semantic subject rather than the head noun. Thus:
mwòˀ ḥák lˀùn kúkòprág
mwòˀfact ḥá-3s.AN.IA-kCOP lˀùnfish kú-3s.AN.TA-kò-3s.AN.TP.REAL.PFV-prágcatch
"(the fact) that he caught fish ..."