first, firstly 和 second, secondly 等，都可以用于列举事实论点，但 firstly 和 secondly 在现代英语中往往用 first 和 second 代替。例如：

First (firstly), the poor girl had no clothes; second (secondly), she had no home; third (thirdly), she had no friends. 首先，这个可怜的女孩没有衣服；其次，她没有家；再次，她也没有朋友。（薄冰：《英语惯用法词典》）