to start with 和 at first 有什么区别

问题描述:

to start with 和 at first 有什么区别
we have lots of work to do today but ______ we'll do the washing-up.
A after all B otherwise C to start with D at first
答案是C我知道是对的,为什么D不对?

自己的理解
to start with “首先”,表示动作的先后顺序.
at first “起初”,一般用来表示和预想的结果不同.