Many linguists have formulated various constraints to define a general rule for code-switching (Poplack, 1978(Poplack, , 1980Belazi et al., 1994).
these constraints cannot be postulated as a universal rule for all code-switching scenarios, especially for languages that are syntactically divergent (Berk-Seligson, 1986), such as English and Mandarin since they have word alignments with an inverted order.