竟 and 境 are both read ging2 in Cantonese, which usually corresponds to a third tone syllable in Mandarin (as is the case for 警, which is ging2 in Cantonese and jing3 in Mandarin). However, both of ...
Schuessler's reconstruction of the Old Chinese reading of 二 is *ńźi. It seems there is a correspondence between OC syllables beginning in *ń or *ńź and Mandarin syllables romanised as er. However, ...