shí / bā / wán / shì / yì / zhǒng / yóu / shí / bā / gè / tàn / yuán / zǐ / zǔ / chéng / de / wán / tīng十八烷是一种由十八个碳原子组成的烷烃。Octadecane is an alkane made up of eighteen carbon atoms.