1
Firstly, + clause
常用于句首，表示列举第一点。
Firstly, we need to gather all the data.
首先，我们需要收集所有数据。
首先
先理解核心含义，再看它在真实句子里的用法。
首先
before anything else
Firstly, we need to gather all the data.
首先，我们需要收集所有数据。
首先
before anything else
Firstly, I would like to thank everyone for coming.
首先，我要感谢大家的到来。
Firstly, wash the vegetables, then cut them into small pieces.
首先，把蔬菜洗干净，然后把它们切成小块。
Firstly, we need to check the weather before planning the trip.
首先，我们需要在计划这次旅行之前查看天气。
常用于句首，表示列举第一点。
Firstly, we need to gather all the data.
首先，我们需要收集所有数据。
置于主语后、动词前，表示顺序。
We should firstly consider the costs.
我们应当首先考虑成本。
与序列词连用，用于分点论述。
Firstly, we need to plan; secondly, we need to execute; thirdly, we need to evaluate.
首先，我们需要计划；其次，我们需要执行；第三，我们需要评估。
Not this
The firstly chapter is easy.
Use this
The first chapter is easy.
firstly是副词，不能修饰名词；应用形容词first修饰chapter。
Not this
Firstly, I was afraid, but then I became brave.
Use this
At first, I was afraid, but then I became brave.
firstly用于列举顺序，不表示时间上的先后；表示‘起初’应用词组at first。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
首先且最重要的
Firstly and foremost, we need to ensure safety.
首先且最重要的是，我们需要确保安全。
首先，让我们
Firstly, let us consider the main issue.
首先，让我们考虑主要问题。
首先，我们需要
Firstly, we need to gather all the data.
首先，我们需要收集所有数据。
首先，重要的是
Firstly, it is important to define the terms.
首先，重要的是定义这些术语。
首先，考虑
Firstly, consider the cost implications.
首先，考虑成本影响。
首先，我想
Firstly, I would like to thank everyone for coming.
首先，我想感谢大家的到来。
首先，你必须用一条鲱鱼砍倒森林里最大的树！
Firstly, let me thank everyone for coming.
首先，让我感谢大家的到来。
Use firstly naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
first（第一）+ ly（副词后缀）→ 首先。联想：第一件事就是“firstly”。
“firstly” 多用于正式文体，如学术写作、演讲或列举论点时，口语中较少使用，更常用 “first” 或 “first of all” 替代。
常用于列举要点时置于句首
Dictionary facts from DICTIONARY_API_DEV, ECDICT, WIKTIONARY.