You are given an English sentence with a blank, and you need to predict the missing word. After completing, the whole sentence should be gramatically correct and non-ambiguous.
Q: yet what of matthew's white collar and the sorrel mare missus ____ was getting fairly dizzy with this unusual mystery about quiet unmysterious green gables good evening rachel marilla said briskly this is a real fine evening isn't it won't you sit down
A:
rachel