first /fɜːrst/ /fɜːst/
foremost /ˈfɔːrmoʊst/ /ˈfɔːməʊst/
firstly /ˈfɜːrst.li/ /ˈfɜːstli/
first of all /fɜrst ʌv ɔl/ /fɜːst ɒv ɔːl/