• Firstly and first (of all) are used to introduce a series of facts, reasons, opinions, etc. * firstly 和 first (of all) 均用以引出一系列事实、理由、意见等：◆The brochure is divided into two sections, dealing firstly with basic courses and secondly with advanced ones. 小册子分为两部分：第一部分涉及基础课程，第二部分涉及高级课程。 Firstly is more common in BrE than in NAmE. * firstly 在英式英语中比在美式英语中更常用。
• At first is used to talk about the situation at the beginning of a period of time, especially when you are comparing it with a different situation at a later period. * at first 用以讲述最初阶段的情况，尤指与后来的不同情况相比较：◆Maggie had seen him nearly every day at first. Now she saw him much less. 起初玛吉几乎每天都见到他，现在见到他的次数少得多了。

Ordering your points 梳理要点

• ◆This study has the following aims: first, to investigate how international students in the UK use humour; second, to examine how jokes can help to establish social relationships; and, third, to explore the role that humour plays in helping overseas students adjust to life in the UK. 本研究有以下几个目的：第一，调查在英国的留学生如何运用幽默；第二，考察笑话如何帮助建立社交关系；第三，探究幽默对留学生适应英国生活所起的作用。
• ◆ Let us begin by identifying some of the popular joke genres in the UK. 首先我们来探究一下流行于英国的一些笑话类型。
• ◆ Next, let us turn to / Next, let us consider the question of gender differences in the use of humour. 接下来，我们来探讨一下运用幽默的性别差异问题。
• ◆ Finally / Lastly, let us briefly examine the role of humour in defining a nation's culture. 最后，我们来简略地探讨一下幽默在界定民族文化中所起的作用。