You use primarily to say what is mainly true in a particular situation.
mainly , principally , chiefly
a book aimed primarily at high-energy physicists.
一本主要以高能物理学家为目标对象的书。
Public order is primarily an urban problem.
公共秩序主要是城市的问题。
Investment remains tiny primarily because of the exorbitant cost of land.
投资仍低迷的主要原因是地价太过高昂。