首先的副词是firstly ；

firstly：adv.(用于列举)第一，首先。

相关介绍

Firstly I compliment you on most of your excellent Spring issue of 'Triangle'.

让我来夸几句，你们《三角迷踪》春季号的大部分内容都非常精彩。

The programme is now seven years behind schedule as a result, firstly of increased costs, then of technical problems

该项目现已经比预定时间晚了7年，原因首先是因为成本增加，其次是由于技术问题。

You need, firstly, a strong independent board of directors and secondly, an experienced and dedicated staff.

你首先需要一个强大的独立董事会，其次需要一批富有经验并且爱岗敬业的员工。

You'd better stay at his department. firstly, you can keep an eye on him and secondly, you can learn something from him.

你最好就留在他那个部门吧，一来可以看着他，二来也可以学点儿东西。

Firstly, they spent more time in search food ．

首先,他们花了更多的时间寻找食物。