处于主导地位英文

英文原文：dominate gradually .英式音标：[ˈdɒmɪneɪt] [ˈgrædʒʊlɪ; ˈgrædjʊəlɪ] . 美式音标：[ˈdɑmɪnet] [ˈgrædʒʊəli] .

It can be seperated in A and B , A is more important

This item comprises A and B, with A being the principal component.

one substance consists of A & B,and A accounts for the main part/and A dominates.以...为主 的表达很多，这里根据具体语境，还是占了主要的部分这样翻比较好

Gradually it starts to play the leading role.