adj .
completely necessary ; vitally important 반드시 필요한 ; 너무나 중요한

• It is _____ that you put out the fire in your hair ; if you don't do it immediately, your scalp will be severely burned.
  네 머리에 붙은 불은 반드시 꺼야 한다 ; 빨리 그렇게 하지 않으면 네 머리 가죽은 심각한 화상을 입을 것이다.
• The children couldn't accept the idea that cleaning up the playroom was _____ ; they said they didn't mind wading through the toys strewn on the floor, even if they did occasionally fall down and hurt themselves.
• 이 단어는 명사로 쓰일 경우, 명령이나 지시, 요구, 의무 책임 등을 뜻한다.
• A doctor has a moral _____ to help sick people instead of playing golf -- unless, of course, it's his day off, or the people aren't very sick.