retention的动词形式
其动词形式为retain retain v. 保持，保留；保存，储存；记住；付定金聘定（尤指律师）；留用（员工） Although most of their scales have been lost, tunas and mackerels retain a patch of coarse scales near the head called the corselet. 虽然它们的大部分鳞片已经消失，但金枪鱼和鲭鱼头部附近仍保留着一块粗糙的鳞片，称为胸甲...