mainstay

1. N-COUNT If you describe something as the mainstay of a particular thing, you mean that it is the most basic part of it. 最基本組成部分[usu 'the' N 'of' n]

Fish and rice were the mainstays of the country's diet. 魚和米是這個國家的主要食物。

This principle of collective bargaining has been a mainstay in labour relations in this country. 這種集躰談判原則已成爲該國勞動關系的一個重要基礎。