Cooperative activity is essential to effective community work.

　　要把社區工作做好，協作活動是必不可少的。

　　It is essential that we present a united front.

　　至關重要的是我們要表現得團結一致。

　　Good posture is essential when working at the computer.

　　用電腦工作時良好的姿勢極其重要。

　　The agreement is essential to spurring economic growth around the world.

　　這項協議對于促進世界經濟的增長是至關重要的。

　　A degree is an essential prerequisite for employment at this level.

　　學位是做這級工作必備的先決條件。