Kau-ōaⁿ-só͘ (Eng-gí: exchange) sī ū-cho͘-chit ê chhī-tiûⁿ, choan-bûn tī chèng-koàn, siong-phín, gōa-kok-gîn kau-ōaⁿ, kî-hòe, kap option ê bé-bē.