полезный

In a sentence

• Этот совет оказался очень полезным.

  This advice turned out to be very useful.

  Here 'полезный' is used to describe 'совет' (advice), indicating that it is helpful or beneficial.

• Я всегда выбираю полезную еду для здоровья.

  I always choose healthy food for my health.

  In this context, 'полезный' modifies 'еду' (food), referring to food that is good for health or well-being.

• Физические упражнения считаются полезными для организма.

  Physical exercises are considered beneficial for the body.

  Here 'полезный' applies to 'упражнения' (exercises), highlighting their beneficial impact on physical health.