ADV 首先;第一 You use firstly in speech or writing when you want to give a reason, make a point, or mention an item that will be followed by others connected with it. 首先;第一
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。
Vitamin C has many roles to play in weight control. Firstly, it is needed for hormone production.